1× 1= 1

1×2=2 ,2×2=4

1×3=3 ,2×3=6 ,3×3=9

1×4=4 ,2×4=8 ,3×4= 12, 4×4= 16

1×5=5, 2×5= 10 ,3×5= 15 ,4×5=20 ,5×5=25

1×6=6 ,2×6= 12,3×6= 18, 4×6=24 ,5×6=30, 6×6=36 , 1×7=7 ,2×7= 14 ,3×7=2 1, 4×7=28, 5×7=35 ,6×7=42, 7×7=49

1×8=8, 2×8= 16 ,3×8=24 ,4×8=32, 5×8=40 ,6×8=48, 7×8=56, 8×8=64

1×9=9, 2×9= 18, 3×9=27 ,4×9=36 ,5×9=45, 6×9=54, 7×9=63, 8×9=72, 9×9=8 1

Second grade formula rules

Factor x factor = product, product present factor+factor, dividend present divisor = quotient, quotient x divisor = dividend, dividend present quotient = divisor.

Integer multiplication calculation rules: multiply the number on each bit of one factor by the number on each bit of another factor, then multiply the number on which bit of the factor, align the end of the multiplied number with which bit, and then add the multiplied numbers.

Decimal multiplication rule: calculate the product according to the calculation rule of integer multiplication, and then look at the factor * * *, how many decimal places there are, count from the right side of the product and point to the decimal point; If the number of digits is not enough, make up with "0".