Round Numbers in Math
A very common task in math is to round numbers to a specified place value. That place value may be to the left or right of the decimal point. Moving left of the decimal point, you encounter the ones, tens, hundreds and then thousands place. Moving to the right of the decimal place, you'll find the tenths, hundredths and thousandths place. The basic rule is that if the number to the right of the rounding-off point is five or greater, round up by one. If that number on the right is zero to four, discard the number and everything to the right, replacing them with zeros.
Instructions
1. Choose a number to round. For example, suppose your teacher gives you the number 15,729 and tells you to round it to the nearest hundred. Circle the hundreds-place digit, 7.
2. Look at the digit to the immediate right of the hundreds place, which is 2. Because it is 4 or lower, simply replace it and the the number to its right with a zero. Keep the 7 in place. The result is 15,700.
3. Try a rounding-up example. Suppose you're told to round 7,345.6189 to the nearest hundredth. So you would circle the hundredth place, in this case 1.
4. Look at the place to the right of the hundredths place to find 8, which is 5 or higher. That means you must round up the 1 to a 2, then substitute zeros for everything to the right.
5. Write down the answer, 7,345.6200. Because the zeros are not relevant to the number's value, you can discard them, so the answer would be 7,345.62.
6. Watch out for chain reactions. For instance, suppose you have to round 39,814 to the nearest thousand. Because the digit in the place to the right of the thousands place is 8, which is 5 or higher, you need to round up. The problem is that you have to increase the 9 in the thousands place, but you can't make it a 10. So you need to increase the 3 in the ten thousands place to a 4 and make the 9 a zero.
Tags: thousands place, number right, decimal point, everything right, increase thousands, increase thousands place