So, if you had two estimates for 31.9, they would be relatively close to the number itself. Here are some estimates:
32.0 ÷ 4 = ?
30.0 ÷ 4 = ?
Okay, so, you have your two rough estimates of what 31.9 ÷ 4 could equal up to. Since 31.9 ÷ 4 equals 7.975. You could divide the estimations by the same number and recieve a close enough answer. Remember, estimations aren't accurate.
32.0 ÷ 4 = 8
30.0 ÷ 4 = 7.5
Now that you see what those quotients are, take a look at the accurate estimate again. You see that 31.9 equals 7.975. Let's look at this closer.
7.975 is really equivalent to 8.0 or 8.
How is that the equivalent? Well, if you take a look at the first two numbers, you'll see that 7.9 can be rounded to 8, leaving the numbers behind it as zeros.
How I remember when to round: 5 and above, give it a shove, 4 and below, keep the number I know.
Basically meaning: If the number isn't above 5, keep the same number you started with.
So, your rough estimate to 31.9 ÷ 4 is equal to 8.
I hope I helped :)
