90
90
35 x 3 = (30 x 3) + (5 x 3) = 90 + 15 = 105
16x9=9x6+9x10=54+90=144
45*60 can be written as (40+5)*60 and the distributive propoerty used to evaluate it. However, the associative property is much better 45*60 = 45*(2*30) = (45*2)*30 = 90*30 = 2700
90
7*9 = 9*(10 - 3) = 90 - 27 = 63
90
90
35 x 3 = (30 x 3) + (5 x 3) = 90 + 15 = 105
90 + 27 = 117
16x9=9x6+9x10=54+90=144
12*90 = 12*(100-10) = 12*100 - 12*10 = 1200 - 120 = 1080.
45*60 can be written as (40+5)*60 and the distributive propoerty used to evaluate it. However, the associative property is much better 45*60 = 45*(2*30) = (45*2)*30 = 90*30 = 2700
Rounding isn't necessary. The distributive property tells you that 13 x 9 = 90 + 27 = 117 If you have to, you could estimate that 10 x 10 = 100
90. You round both numbers up.
9