FOUR BASIC ARITHMETIC OPERATIONSReview of Introductory MathematicsThus, the difference of 5 - 3 is not the same as 3 - 5. The associative law for addition permittedcombining addends in any order. In subtraction, this is not allowed.(a-b)-c a-(b-c)Example: (10-5)-1 10-(5-1)4 6When subtracting two numbers, the subtrahend is placed under the minuend with the digitsarranged in columns placing the units place under the units place, the tens column next, and soon.Example:Subtract 32 from 54.Solution:54-3222Whenever the digit in the subtrahend is larger than the digit in the minuend in the same column,one place value is borrowed from the next digit to the left in the minuend. Refer to thefollowing example.Example:Subtract 78 from 136.Solution:213/6-7858When subtracting the units column, 6 - 8, a 10 is borrowed from the tens column. Thisnow makes subtracting the units column 16 - 8. An 8 is placed under the units column.Next the tens column is subtracted.A 10 was borrowed from the tens column and now 7 is subtracted from 12, not 13. Thisyields: 12 - 7 = 5. The 5 is placed under the tens column and the difference is 58.This can be done for any subtraction formula. When the digit in the subtrahend columnis larger than the digit in the minuend in the same column, a number from the next higherplace position column is "borrowed." This reduces the higher position column by one.MA-01 Page 10 Rev. 0

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