Mental Mathematics

Left to Right Addition: Add from left to right instead of right to left for faster mental calculation

Adding with 9: To add 9 to any number, add 10 and subtract 1

Grouping: Group numbers that add up to 10 or multiples of 10

Break and Add: Break larger numbers into smaller, easier parts

Complement Method: Use complements to 10 for easier subtraction

Adding Up: Instead of subtracting, add up from the smaller to larger number

Break Apart: Break the number being subtracted into easier parts

Round and Adjust: Round to nearest 10, then adjust the result

Multiply by 11: For 2-digit numbers, add the digits and place between them

Multiply by 5: Multiply by 10 and divide by 2

Multiply by 25: Multiply by 100 and divide by 4

Squares ending in 5: For numbers ending in 5, multiply the first digit by (first digit + 1) and add 25

Divide by 5: Multiply by 2 and divide by 10

Divide by 25: Multiply by 4 and divide by 100

Factor Method: Break the divisor into factors for easier division

Estimation: Use estimation to check if your answer is reasonable