Question

The age of earth’s crust is 5 · 10^9 years. Express this number as an integer.

Answer 1

5,000,000,000 (see below)

Explanation:

Integers are whole numbers and their opposites. That doesn't include fractions or decimals, even if they're negative. Being negative doesn't do anything, really.

For example, 5 and –5 are integers, but 5.1 or –5.3 are not integers. They're decimals, which means they're rational.

Integers also include 0.

Whole numbers do not include 0, so they're only 1, 2, 3, 4, 5, 6, 7, 8, 9 . . . and so on.

All whole numbers are integers.

So in order to find 5 ×
`10^(9)` as an integer, you'll have to multiply the 5 and
`10^(9)` together.

`10^(9)` is simply nine zeros, so it's: 1,000,000,000.

5 × 1,000,000,000 = 5,000,000,000

5,000,000,000 is not a decimal or fraction—and it also isn't negative. That means it's a whole number. Which qualifies it as an integer as well.