SHREE BALAJI CLASSES

 Condition :   This trick is used when we multiply quickly two  numbers with 5 as the unit digit.       Example.  75 × 95 , 95 × 85 ,115 × 145 , 125 × 105 Illustration 1 :     75 × 95 Solution:     Numbers                 Split   as      75                        7      /     5   ×  95                         9      /       5 [Split the numbers keeping the last digit (5) aside]                         1st part  /  2nd part  Product + Sum  ÷  2  /  25        [ Product  and  Sum  of no. other then unit digits] [The 2nd part would be 25 as the sum 7 + 9 =16 is even, if sum is odd , it would have become 75].                           step 1→     7 × 9 +16 ÷ 2  /   25 step 2→     63+8           /    25 step 3→     71              /    25 Answer is 7125 Illustration 2 :     175 × 105 Solution:     Numbers              Split as     175                    17    /    5 ×  105                     10    /    5 [Split the numbers keeping the last di

Condition :   This trick is used when we multiply quickly two  numbers and a number is made by digit 9. Example.  75 × 99 , 95 × 999 ,115 × 99 , 1259 × 999 Illustration 1 :     175 × 999 Solution:           1st part  /  2nd part  step 1→     175-1  / step 2→     174    /    999-174 step 3→     174     /    825 Answer is 174825 Illustration 2 :     258 × 99999 Solution:           1st part  /  2nd part  step 1→     258-1  / step 2→     257     /    99999-257 step 3→     257     /    99742 Answer is  25799742 Illustration 3 :     564 × 99 Solution:           1st part  /  2nd part step 1→     564-1           /   No step 2→     563              /   No step 3→     56399-563  /   No Answer is 55836 « Previous Next »

Condition :   This trick is used when we multiply quickly two similar numbers with unit digit adding up to 10.( All digits are similar other then unit digit) Example.  57 × 53 , 91 × 99 ,114 × 116 , 102 × 108 Illustration 1 :     107 × 103 Solution:           1st part  /  2nd part (2 digits) step 1→ 10 × (10+1)  /    7 × 3 step 2→ 10 × 11         /    21 step 3→ 110              /    21 Answer is 11021 Illustration 2 :     119 × 111 Solution:           1st part  /  2nd part (2 digits) step 1→ 11 × (11+1)  /    9 × 1 step 2→ 11 × 12        /    09 (because 2nd part of 2 digits) step 3→ 132              /    09 Answer is 13209 Illustration 3 :     152 × 158 Solution: 1st part  /  2nd part (2 digits) step 1→ 15 × (15+1)  /    2 × 8 step 2→ 15 × 16         /    16 step 3→ 240              /  16 Answer is 24016 Illustration 4 :     64 × 66 Solution:           1st part  /  2nd part (2 digits) step 1→ 6 × (6+1)  /    4 × 6 step