Basic HTML Version

|  | Table of Contents |  | View Full Version

Page 64 - Touchpad Mathematics_Ver1.0_C4
P. 64

    Subtraction with regrouping

                Example 1. Subtract 1351 from 2089.
                Solution.

                Step 1.  Subtract the ones. 9 – 1 = 8 ones                                             Th H      T O
                Step 2.  Subtract the tens. 8 – 5 = 3 tens
                Step 3.   Subtract the hundreds. 0 hundreds < 3 hundreds,                               1   10
                           so, regroup thousands and hundreds.                                          2   0   8    9
                           2 thousands 0 hundreds = 1 thousand 10 hundreds                         –    1   3   5    1

                           Now, 10 – 3 = 7 hundreds.
                Step 4.  Subtract the thousands. 1 – 1 = 0 thousands                                   0    7   3    8

                So, 2089 – 1351 = 738.

                Example 2. Find the difference of 9544 and 7659.
                Solution.
                Step 1.   Subtract the ones. 4 ones < 9 ones, so, regroup tens
                           and ones.                                                                   Th H      T O

                           4 tens 4 ones = 3 tens 14 ones                                                   14  13
                           Now, 14 – 9 = 5 ones.                                                        8   4   3    14
                Step 2.   Subtract the tens. 3 tens < 5 tens, so, regroup                              9    5   4    4
                           hundreds and tens.

                           5 hundreds 3 tens = 4 hundreds 13 tens                                  –    7   6   5    9
                           Now, 13 – 5 = 8 tens.                                                        1   8   8    5

                Step 3.   Subtract the hundreds. 4 hundreds < 6 hundreds, so,
                           regroup thousands and hundreds.

                           9 thousands 4 hundreds = 8 thousands 14 hundreds
                           Now, 14 – 6 = 8 hundreds.

                Step 4.  Subtract the thousands. 8 – 7 = 1 thousand
                So, 9544 – 7659 = 1885.                                                Interesting Facts

                Subtracting 10, 100 and 1000 from a number                             •   Subtracting 0 from any
                                                                                         number gives that number
                When 10, 100 and 1000 are subtracted  from a                             itself.
                number the digit in its tens, hundreds and thousands                       12 - 0 = 12    187 - 0 = 187
                place respectively decreases by 1.                                     •   Subtracting a number from
                Examples.  a.  235  –  10  =  225                                        itself results in zero.
                                                                                           15 - 15 = 0    239 - 239 = 0
                                                                                       •   Subtracting 1 from a number
                              b.  5701  –  100  =  5601                                  gives the predecessor of the

                                                                                         number.
                              c.  9876  –  1000  =  8876                                   55 - 1 = 54    120 - 1 = 119

                       62        Mathematics 3

| 59 60 61 62 63 64 65 66 67 68 69 |