Use this algorithm in your head:
Take 16 * 18 for an example:
1) Add 16 + 8 = 24
2) Multiply it by 10: 24 * 10 = 240
3) Add up the product of 6 and 8: 240 + (6 * 8) = 288
16 * 18 = 288
Another example:
14 * 17 = ?
1) Add 14 + 7 = 21
2) Multiply it by 10: 21 * 10 = 210
3) Add up the product of 4 and 7: 210 + (4 * 7) = 238
14 * 17 = 238
Take 16 * 18 for an example:
1) Add 16 + 8 = 24
2) Multiply it by 10: 24 * 10 = 240
3) Add up the product of 6 and 8: 240 + (6 * 8) = 288
16 * 18 = 288
Another example:
14 * 17 = ?
1) Add 14 + 7 = 21
2) Multiply it by 10: 21 * 10 = 210
3) Add up the product of 4 and 7: 210 + (4 * 7) = 238
14 * 17 = 238
| Share | Tweet |
Total GMAT Math
Discrete Mathematics: Mathematical Reasoning and Proof with Puzzles, Patterns, and Games
Thinking About Equations: A Practical Guide for Developing Mathematical Intuition in the Physical Sciences and Engineering
No comments:
Post a Comment