Add each digit to its neighbor.
Example: 23 × 11 → 2 _ 3 → 2+3=5 → Answer: 253
Practice: 45 × 11, 67 × 11
Double each digit and add its neighbor.
Example: 34 × 12 → Double 4 = 8 + 3 = 11, Double 3 = 6 → 3 6 8 → Answer: 408
Practice: 23 × 12, 56 × 12
Half the number and add a zero.
Example: 48 × 5 → Half of 48 is 24 → Add zero: 240
Practice: 36 × 5, 82 × 5
Multiply by 10 then subtract the number.
Example: 32 × 9 → 32 × 10 = 320 → 320 − 32 = 288
Practice: 45 × 9, 76 × 9
Double the number twice.
Example: 13 × 4 → 13 × 2 = 26, 26 × 2 = 52
Practice: 15 × 4, 27 × 4
Divide by 4 and add two zeros.
Example: 20 × 25 → 20 ÷ 4 = 5 → Add two zeros: 500
Practice: 40 × 25, 12 × 25
Multiply by 100 then subtract the number.
Example: 47 × 99 → 47 × 100 = 4700 → 4700 − 47 = 4653
Practice: 58 × 99, 23 × 99
Multiply the first digit(s) by the next number, add 25.
Example: 35² → 3 × 4 = 12 → Add 25 → 1225
Practice: 45², 65²
Multiply by 10, then add half the number.
Example: 40 × 15 → 40 × 10 = 400, Half of 40 = 20, 400 + 200 = 600
Practice: 20 × 15, 36 × 15
Multiply and divide back to check.
Example: 23 × 11 = 253 → 253 ÷ 11 = 23 ✅
Practice: 12 × 11, then check; 15 × 9, then check