90+90 equals what

Question

I need help with additon and mutiply and subtraction

Answer 1

that's the same as 2 times 90 = 180

2x9 = 18 and add the 0 to it to get 180

or put the two number, one under the other

90

90

add the one column 0+0 = 0

then add the tens column 9+9 = 18

put them together 180