1Double it three times
To multiply by 8, double the number, double again, and double once more. 8 × 6: 6 → 12 → 24 → 48. 8 × 7: 7 → 14 → 28 → 56. It takes a few seconds, but it is reliable, and each step uses only doubling. If your child already knows the 4s, they can skip a step: double the 4s answer (4 × 7 = 28, so 8 × 7 = 56).
2Ten groups minus two groups
Eight is two less than ten. So 8 × 7 is 70 minus 14, which is 56. 8 × 9 is 90 minus 18, which is 72. This works well for children who are comfortable with subtraction.
3Watch the last digits: 8, 6, 4, 2, 0
The last digits of the 8s count down by 2 and repeat: 8, 16, 24, 32, 40, 48, 56, 64, 72, 80. If your child knows the ending to expect, an answer like 8 × 6 = 46 stands out as wrong: 8 × 6 should end in 8.
48 × 8 = 64, "I ate and ate till I was sick on the floor"
Some children like a silly rhyme: "8 and 8 (I ate and ate) till I was sick on the floor: 64." If rhymes are not your child's thing, use doubling instead: double 8 is 16, double 16 is 32, double 32 is 64.