CALCULATION SPEED TRAINER
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How to use the drill: Press START. A question appears. Type your answer. Press Enter. Next question appears immediately. 60 seconds. Get as many correct as you can. Do this every day before starting study. Your score will increase week by week.
Your Progress This Week
Learn these in order: Tables 1-10 first (2 weeks). Then 11-20 (2 more weeks). Test yourself by covering one column and reciting. Go backwards too, "what × 8 = 96?"
Tables 1 to 20, Complete Reference
| × | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 |
|---|
Tricky Ones to Memorise, These Trip People Up
Often Forgotten
| Sum | Answer |
|---|---|
| 7 × 8 | 56 |
| 7 × 12 | 84 |
| 7 × 13 | 91 |
| 8 × 12 | 96 |
| 8 × 13 | 104 |
| 9 × 13 | 117 |
| 11 × 13 | 143 |
| 12 × 13 | 156 |
| 13 × 14 | 182 |
| 14 × 16 | 224 |
| 17 × 18 | 306 |
| 19 × 18 | 342 |
Important for CAT
| Sum | Answer |
|---|---|
| 15 × 15 | 225 |
| 15 × 16 | 240 |
| 12 × 15 | 180 |
| 16 × 16 | 256 |
| 17 × 17 | 289 |
| 18 × 18 | 324 |
| 19 × 19 | 361 |
| 20 × 20 | 400 |
| 14 × 15 | 210 |
| 11 × 19 | 209 |
| 13 × 17 | 221 |
| 16 × 18 | 288 |
Why squares matter in CAT: P&C questions use n², geometry uses area formulas (all squares), number system uses perfect squares. If you know squares up to 25 by heart, 20% of QA becomes faster instantly.
Squares, 1 to 30
Cubes, 1 to 15
Powers of 2
| 2¹ | 2² | 2³ | 2⁴ | 2⁵ | 2⁶ | 2⁷ | 2⁸ | 2⁹ | 2¹⁰ | 2¹¹ | 2¹² |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 2 | 4 | 8 | 16 | 32 | 64 | 128 | 256 | 512 | 1024 | 2048 | 4096 |
Powers of 3
| 3¹ | 3² | 3³ | 3⁴ | 3⁵ | 3⁶ | 3⁷ |
|---|---|---|---|---|---|---|
| 3 | 9 | 27 | 81 | 243 | 729 | 2187 |
This table is worth 30 seconds per question. When you see "33.33% of 240", your brain should instantly say "1/3 of 240 = 80" without any calculation. Memorise all of these until they're automatic.
Fractions ↔ Percentages, Complete Table
| Fraction | % Value | Decimal | Memory Trick |
|---|---|---|---|
| 1/2 | 50% | 0.5 | Half, everyone knows this |
| 1/3 | 33.33% | 0.333 | 33 and 1/3, memorise the fraction |
| 2/3 | 66.67% | 0.667 | Double of 1/3 |
| 1/4 | 25% | 0.25 | Quarter, half of half |
| 3/4 | 75% | 0.75 | Three quarters |
| 1/5 | 20% | 0.2 | Divide by 5 = multiply by 20% |
| 2/5 | 40% | 0.4 | Double of 1/5 |
| 3/5 | 60% | 0.6 | Triple of 1/5 |
| 4/5 | 80% | 0.8 | Quadruple of 1/5 |
| 1/6 | 16.67% | 0.1667 | Half of 1/3 (33.33/2) |
| 5/6 | 83.33% | 0.8333 | 1 - 1/6 |
| 1/7 | 14.28% | 0.1428 | Difficult, memorise directly |
| 1/8 | 12.5% | 0.125 | Half of 1/4 (25/2) |
| 3/8 | 37.5% | 0.375 | Triple of 1/8 |
| 5/8 | 62.5% | 0.625 | Half + 1/8 |
| 7/8 | 87.5% | 0.875 | 1 - 1/8 |
| 1/9 | 11.11% | 0.111 | Repeating 1s (0.111...) |
| 1/10 | 10% | 0.1 | Divide by 10 |
| 1/11 | 9.09% | 0.0909 | Repeating 09s |
| 1/12 | 8.33% | 0.0833 | Half of 1/6 |
The 10% Method, Fastest % Calculation
10% Method, Never Calculate Directly
Find 10% first (divide by 10). Then build any % from 10% chunks.
15% of 340 =
10% = 34, 5% = 17 → 51
22% of 450 =
20% = 90, 2% = 9 → 99
35% of 280 =
30% = 84, 5% = 14 → 98
17.5% of 240 =
10%=24, 5%=12, 2.5%=6 → 42
Learn one shortcut per day. Don't try all at once. Use it on 20 random numbers until it's automatic. Then learn the next one.
Multiplication Shortcuts
×11 Trick, Instant
Add adjacent digits and place the sum in the middle. If sum ≥ 10, carry the 1.
32 × 11 =
3 (3+2) 2 = 352
54 × 11 =
5 (5+4) 4 = 594
47 × 11 =
4 (4+7) 7 → carry → 517
83 × 11 =
8 (8+3) 3 → carry → 913
×5 Trick, Halve then ×10
Divide the number by 2, then multiply by 10. Always faster than ×5 directly.
68 × 5 =
68÷2 = 34, ×10 = 340
136 × 5 =
136÷2 = 68, ×10 = 680
93 × 5 =
93÷2 = 46.5, ×10 = 465
248 × 5 =
248÷2 = 124, ×10 = 1240
×25 Trick, Divide by 4 then ×100
Multiply by 25 = divide by 4 then add two zeros.
48 × 25 =
48÷4 = 12, ×100 = 1200
36 × 25 =
36÷4 = 9, ×100 = 900
52 × 25 =
52÷4 = 13, ×100 = 1300
76 × 25 =
76÷4 = 19, ×100 = 1900
Squaring Numbers Ending in 5
n5² = n×(n+1) followed by 25. Works for any number ending in 5.
35² =
3×4=12, then 25 → 1225
45² =
4×5=20, then 25 → 2025
65² =
6×7=42, then 25 → 4225
85² =
8×9=72, then 25 → 7225
Multiply Numbers Near 100
Find how far each number is from 100. Subtract cross-wise for first part. Multiply differences for second part.
97 × 96 =
97-4=93, 3×4=12 → 9312
98 × 93 =
98-7=91, 2×7=14 → 9114
94 × 92 =
94-8=86, 6×8=48 → 8648
103 × 106 =
103+6=109, 3×6=18 → 10918
Divisibility Rules, All 9 in One Place
Mental check without division.
÷ 2
Last digit even
÷ 3
Sum of digits ÷ 3
÷ 4
Last 2 digits ÷ 4
÷ 5
Ends in 0 or 5
÷ 6
Divisible by 2 AND 3
÷ 8
Last 3 digits ÷ 8
÷ 9
Sum of digits ÷ 9
÷ 11
Alternate sum diff ÷ 11
BODMAS, Order of Operations
B
Brackets
O
Orders
D
Division
M
Multiply
A
Addition
S
Subtract
10 minutes every morning before anything else. This is the only rule. Before opening Parth's video, before reading notes, before any QA question, 10 minutes of calculation practice. 10 minutes a day for 5 months = 25+ hours of speed training. That's the difference.
Month-by-Month Focus
Jun
Month 1
Tables 1-12 + Squares 1-15 + Fractions 1/2 to 1/10
Jul
Month 2
Tables 13-20 + Squares 16-25 + All fractions + ×11 trick
Aug
Month 3
Squares 26-30 + Cubes + ×5 ×25 shortcuts + 10% method
Sep+
Month 4+
Everything together, mixed drills, approximation, speed
Exact Daily 10-Minute Routine
Minutes 0-3: Formula Recall
- Close all books. Write from memory: today's QA topic formulas + 5 fraction-% conversions.
- Check against your notes. Whatever you forgot, re-write 3 times, then close and recall again.
- This is not optional. Memory under pressure (exam) requires automatic recall. Building it takes repetition.
Minutes 3-7: Speed Drill (Use this app)
- Open the Daily Drill tab. Press START. Do 60 seconds of mixed questions.
- Track your score every day in your notebook. Date → Score → Types wrong.
- Week 1 target: 8-12 correct. Week 4 target: 18-22 correct. Month 3 target: 28+ correct.
Minutes 7-10: This Week's Shortcut Practice
- Pick ONE shortcut for this week (×11, ×5, ×25, near-100, etc.)
- Apply it to 10 random numbers you make up on the spot. Time yourself.
- Move to the next shortcut only when you can do the current one without thinking.
Weekly Targets, Track These Every Week
| Week | Tables Target | Drill Score | Fraction Test | Shortcut |
|---|---|---|---|---|
| Week 1 (Jun 15) | 1-12 fluent | 8-12 | 1/2 to 1/6 instant | ×11 trick |
| Week 2 (Jun 22) | 1-15 fluent | 12-16 | 1/2 to 1/10 instant | ×5 trick |
| Week 3 (Jun 29) | 1-17 fluent | 15-18 | All fractions instant | ×25 trick |
| Week 4 (Jul 6) | 1-20 fluent | 18-22 | All + % mental calc | Square of n5 |
| Week 8 (Aug 3) | 1-20 automatic | 22-26 | Instant always | Near-100 |
| Week 12 (Sep 1) | All automatic | 26-32 | Instant + approximation | All shortcuts |
Signs You're Improving
Week 2: Tables 1-12 feel automatic. You don't have to think for 7×8 anymore.
Week 4: You can calculate 15% of any 3-digit number in your head in under 5 seconds.
Week 8: When you see "33.33% of 450", your brain says "1/3 of 450 = 150" instantly without thinking "percentage".
Week 12: Your QA question solving time drops from 3 minutes to under 90 seconds for Arithmetic questions. That is the payoff of 10 minutes every morning.
The honest truth: You will not see improvement in week 1. You might not in week 2 either. The improvement comes suddenly in week 3-4 when the repetition crosses a threshold and things start feeling automatic. Trust the daily 10 minutes. Show up every day. The compound effect of repetition is real.