Number System

Fast trick to solve number system

Q .Find the unit digit in (439 - 769 ).

STEP 1 :

As we know to calculate unit digit first of all we calculate 4 multiples of the numbers

so divide the power of the numbers with 4-

if we divide 39 with 4 then reminder will be 3 so the 3 multiple value of 4 is 64

39 / 4 = 9 * 4 + 3

so unit place for 439 = 14

if we divide 69 with 4 then reminder will be 1 so the 1 multiple value of 7 is 7

69 / 4 = 17 * 4 + 1

so unit place for 769 = 7

STEP 2 :

439 - 769

Now subtract above calculated unit digit to calculate the final unit digit-

14 - 7 = 7

Unit digite is 7