Subjects
Is there an easy trick for multiplying by 9?
Updated: 11-Apr-2025

For single-digit numbers ×9, use your fingers or remember that 9×n = (n−1) and (10−(n−1)). For example, 9×7: 7−1 = 6, 10−6 = 3 → 63. It also helps to note 9 × n = 10 × n − n, which makes mental calculation easier.

Leave a Comment
Please enter your name.
Please enter a valid email address.
Please write a comment.
Comment submitted successfully!
Related questions
Q: What’s a mental trick for multiplying two-digit numbers close to 100?
Subtract each from 100, cross-subtract, then multiply differences. Example: 98×97 → 98−3, 97−2, 95 | 6 = 9506. This Vedic math trick is fast for numbers near 100.....
Q: Can you mentally divide numbers by 5 easily?
Yes, multiply the number by 2, then divide by 10. For example, 135 ÷ 5: 135 × 2 = 270 → 270 ÷ 10 = 27. This trick is fast....
Q: How can I double numbers quickly?
To double a number, split it into parts. For 68: double 60 = 120, double 8 = 16, total = 136. This method makes mental doubling of larger numbers faster....
Q: Any tip for adding large numbers mentally?
Break numbers into smaller parts using rounding and compensation. For example: 498 + 327 = (500 + 327) − 2 = 825. Adjusting and rounding mentally simplifies the process and....
Q: How do you quickly find 10% of a number?
To find 10%, just move the decimal point one place to the left. For example, 10% of 320 is 32. This simple trick is helpful for quick estimations in tips,....
Q: How can I subtract numbers quickly from 1000?
To subtract from 1000, subtract each digit from 9, except the last digit from 10. For 1000 − 648: 9−6 = 3, 9−4 = 5, 10−8 = 2 → answer:....
Q: What’s a shortcut for multiplying numbers by 11?
To multiply a two-digit number by 11, add the digits and place the sum between them. Example: 23 × 11 = 2 (2+3) 3 = 253. If the middle digit....
Q: How can you square a number ending in 5 mentally?
For numbers ending in 5, like 25, multiply the first digit(s) by the next higher number, then append 25. For example, 25²: 2 × 3 = 6, then write 625.....
Q: What’s the trick to multiplying numbers by 5 quickly in your head?
To multiply any number by 5 mentally, divide it by 2 and multiply by 10. For example, 36 × 5: half of 36 is 18, and 18 × 10 is....
Trending Questions