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When adding or subtracting, line up the decimals. Watch for numbers without decimals. THEY ARE WHOLE NUMBERS. Their decimals are at the end like a period at the end of a sentence. 3 + 5.9 + 2.3 would be as follows... Put a decimal behind the 3. 11.2 1 3.0 5.9 2.3 9 + 3 = 12 Carry the one. 4.6 + 5 + 9.7 becomes... + 4 . 6
9 . 7 . 54.93 + 4.98 = 6.3 + 7 + 5.9 = When subtracting decimals, still line up the decimals making sure to put decimals behind any whole numbers. If the top digit is smaller than the bottom digit in a place value, you must rename. 5.0 - 1.23.8 4 10 4.0 -2.6
8.4 -2.8
6 - 3.7 = 100 - 4.5 = When multiplying, we do not need to line up decimals. Multiply as if the decimals are not there. Then count how many digits are behind the decimals for each factor. Make sure the answer has the same number behind it. 3.4 x .04 is as follows. 0.136 3.4 x 0.04 three place values one place value two place value + Fill in your work. 3.25 x 0.4 .In 4.23 x 3.7 how many places are behind the decimal in your answer? place values left Multiply. 3.2 x .7 Fill in all 9 missing digits. 3 . 4 2 x 1.4 1 3 8
.7 4.6 3 x 1 3.4 Needs to move Doesn't need to move. Since we can't divide by a decimal, if the divisor is a decimal, move the decimal to the end to make it a whole number. THEN, MOVE THE SAME NUMBER OF PLACES VALUES IN THE DIVIDEND. If a number has no visible decimal, its a whole number. Its decimal is at the end. 1.6 8 . 5. . . 16 .8 .05 0.057 0.57 5.7 Select the answer with the decimal in the correct place. 23 1.311 57 9.135 ÷ 4.5 = |