VIDEO: Calculating with a rollover

Preparations for calculating with approximate numbers

• When calculating with a rollover, you should note that Counting but you do not need to follow the rules for rounding. For you this means that numbers from 1 to 4 are not rounded down and numbers from 5 to 9 are not rounded up, but the rounding is adapted to the math problems.
• Remember that when calculating with a rough estimate, you often have to make an estimate. You should take into account that estimating is not to be confused with guessing, but that variables to be determined must be related to known guide values.

Find mathematical solutions with a rollover

If you calculate addition and subtraction problems with an estimate, they should be rounded in such a way that the sum or difference can be easily determined.

• When calculating 213 + 178 + 378, it is beneficial to round to full hundreds: 200 + 200 + 400 = 800.
• It is also possible to mix rounded numbers with exact numbers so that you get a more accurate result: 200 + 178 + 400 = 778.
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Rough calculation for division

Division, i.e. dividing multi-digit numbers, is not an easy one ...

• When calculating multiplication problems, rounding up and down is also beneficial for you to get a quick approximate result: 213 _* 178 rounds to 200 _* 200 = 40000.
• When calculating division problems, you will quickly get a rounded result if you round the dividend so that it can be easily divided by the divisor. If you want to divide 2948 by 40, you should not round up 2948 to 3000, but round down to 2800 and get the result 70 with the rollover.
• You can also use arithmetic with rollover for all other types of arithmetic such as exponentiation or square root.