Age 89
Multiply a number by 9 or 11 by multiplying by 10 and adding or subtracting the number.
Multiply by 9 or 11
Multiply a twodigit number by singledigit number, multiplying the tens first.
Multiply
Age 910
Multiply a number by 9, 11, 19 or 21 by multiplying by 20 and adding or subtracting the number.
Multiply by 9, 11, 19 or 21
Multiply a twodigit number by singledigit number, multiplying the tens first.
Multiply
Age 1011
Multiply a number by 49, 51, 99 or 101 by multiplying by 50 or 100 and adding or subtracting the number.
Multiply by 49, 51, 99 or 101
Multiply a twodigit number by singledigit number, multiplying the tens first.
Multiply
