4 Mental Math Shortcuts That Make You Feel Like a Genius
Calculate faster than a smartphone with these ancient Vedic and modern mental math algorithms.
Multiply Any 2-Digit Number by 11 in 2 Seconds
To multiply any two-digit number by 11, simply split the two digits and insert their sum right in the middle.
1. Separate 3 and 5 → [3 _ 5]
2. Add the digits: 3 + 5 = 8
3. Place 8 in the middle → 385
If the sum is 10 or greater (e.g. 78 × 11), keep the last digit in the middle and carry the 1 over to the first digit (7 + 1 = 8, so 858).
Try the 11-Multiplier Trick Yourself
Type any two-digit number to see it solved instantly:
Instant Squaring of Numbers Ending in 5
Squaring numbers like 25, 35, 65, or 85 can be performed instantly in your head with this simple rule: the answer always ends in 25.
1. Take the first digit (6) and multiply it by the next whole number (6 + 1 = 7) → 6 × 7 = 42
2. Append 25 to the result → 4,225
Another test: 85² → 8 × 9 = 72, then append 25 → 7,225.
The "All From 9 and the Last From 10" Subtraction Rule
When subtracting any number from a base of 1,000, 10,000, or 100,000, subtract every digit from 9, and only the final non-zero digit from 10.
1. 9 − 6 = 3
2. 9 − 4 = 5
3. 10 − 7 = 3
Answer: 353
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