Question

Given the expression: 1990 x 1991 - 1989 x 1990. What counting number is equivalent to the expression?

Answer 1

Do you know distributive property of multiplication? That solves this problem quite fast.

Answer 2

yeah

Answer 3

dont you need parentheses for that though?

Answer 4

So you know that your given expression is equivalent to
\[1990 \times(1991-1989)\]
correct?

Answer 5

yeah

Answer 6

So 1991-1989=2, so that your original expression is the same as 1990x2=2980.

Answer 7

Oh ok. Thanks