Question 328866
Add and subtract: line up the numbers so decimal point are above each other. 
Start from the right hand side and work to the left. 
If their is not a number in the place above or below a number to the right of the decimal point, add a zero.
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{{{addition_cartoon( 2.3456, 8.15 )}}}
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{{{subtraction_cartoon( 17.7524, 1.795699 )}}}
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Multiplication is a little different. 
Count the decimal places for each number and sum them. 
{{{1.23=2}}}decimal places
{{{4.556=3}}}decimal places
Total number of decimal places ={{{5}}}
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Now multiply the numbers without decimal. 
{{{123*6+123*50+123*500*123*4000=738+6150+61500+492000=560388}}}
Now start from the far right of the number and move over 5 places, the number of decimal places you counted before.
560388
56038.8<--- 1
5603.88<--- 2
560.388<--- 3
56.0388<--- 4
5.60388<--- That's 5.
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1.23 x 4.556=5.60388
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How's that?