How to do mental math fast multiplication?
The Left-to-Right Method
Start by multiplying the largest place values first instead of working backwards from the ones place. For instance, when multiplying 43 by 8, multiply 40 by 8 to get 320, then multiply 3 by 8 to get 24. Adding 320 and 24 gives you 344 right away.
Rounding and Compensation
When a number sits right next to a round figure like 10, 60, or 100, round it up, run the multiplication, and subtract the extra amount. If you need to solve 59 times 6, treat 59 as 60 minus 1. Multiply 60 by 6 to get 360, then subtract 6 to land on 354. This technique is one of the easiest ways to use math in daily life when calculating totals and discounts on the go.
The Break-Apart Method
Keep one number intact and split the second number into tens and ones. To figure out 54 times 23, split 23 into 20 and 3. Calculate 54 times 20 to get 1,080, calculate 54 times 3 to get 162, and combine them for a final total of 1,242.
Quick Shortcuts
Two specific number patterns make calculation even faster:
- To multiply any number by 5, multiply it by 10 first and divide the result by 2, turning 86 times 5 into 860 divided by 2, which is 430.
- To square any two-digit number ending in 5, multiply the first digit by the next consecutive integer and place 25 at the end, meaning 75 squared becomes 7 times 8 (56) followed by 25, giving 5,625.
