Remember:
| $\times$ | $2$ | $3$ | $4$ | $5$ | $6$ | $7$ | $8$ | $9$ |
| $2$ | $4$ | $6$ | $8$ | $10$ | $12$ | $14$ | $16$ | $18$ |
| $3$ | $6$ | $9$ | $12$ | $15$ | $18$ | $21$ | $24$ | $27$ |
| $4$ | $8$ | $12$ | $16$ | $20$ | $24$ | $28$ | $32$ | $36$ |
| $5$ | $10$ | $15$ | $20$ | $25$ | $30$ | $35$ | $40$ | $45$ |
| $6$ | $12$ | $18$ | $24$ | $30$ | $36$ | $42$ | $48$ | $54$ |
| $7$ | $14$ | $21$ | $28$ | $35$ | $42$ | $49$ | $56$ | $63$ |
| $8$ | $16$ | $24$ | $32$ | $40$ | $48$ | $56$ | $64$ | $72$ |
| $9$ | $18$ | $27$ | $36$ | $45$ | $54$ | $63$ | $72$ | $81$ |
If you have trouble remembering $56 = 7\times 8$, just think ‘$5678$’.