6th Class Mathematics Playing with Numbers

  • question_answer 20)
    Using divisibility tests, determine which of the following numbers are divisible by 6? (a) 297144                           (b) 1258                                (c) 4335                                (d) 61233 (e) 901352                           (f) 438750                            (g) 1790184                         (h) 12583 (i) 639210                             (j) 17852

    Answer:

                    We know that, a number is divisible by 6, if it is divisible by 2 and 3 both. Also, a number is divisible by 2 if it has any of the digits 0, 2, 4, 6 or 8 in its ones place and number is divisible by 3, if the sum of the digits is a multiple of 3. (a) We have, 297144 (i) Divisibility by 2 \[\because \] Units digit of number = 4, so 297144 is divisible by 2. (ii) Divisibility by 3 Sum of digits of given number = 2 + 9 + 7 + 1 + 4 + 4 = 27 \[\because \] 27 is divisible by 3, so 297144 is also divisible by 3. Now, we see that 297144 is divisible by 2 and 3 both. Hence, it is divisible by 6. (b) We have, 1258 (i) Divisibility by 2 \[\because \] Units digit of number = 8, so 1258 is divisible by 2. (ii) Divisibility by 3 Sum of digits of given number = 1 + 2 + 5 + 8 = 16 16 is not divisible by 3, so 1258 is not divisible by 3. Now, we see that 1258 is divisible by 2 but not divisible by 3. Hence, it is not divisible by 6. (c) We have, 4335 (i) Divisibility by 2 \[\because \]Units digit of number = 5 which is not any of the digits 0, 2, 4, 6 or 8. \[\therefore \] 4335 is not divisible by 2. (ii) Divisibility by 3 Sum of digits of given number = 4 + 3 + 3 + 5 = 15 \[\because \] 15 is divisible by 3, so 4335 is divisible by 3. Now, we see that 4335 is divisible by 3 but not divisible by 2. Hence, it is not divisible by 6. (d) We have, 61233 (i) Divisibility by 2 \[\because \] Units digit of number = 3 which is not any of the digits 0, 2, 4, 6 or 8. \[\therefore \] 61233 is not divisible by 2. Now, we have no need to check the given number is divisible by 3 or not because it is not divisible by one of the factors of 6. Hence, the given number 61233 is not divisible by 6. (e) We have, 901352 (i) Divisibility by 2 \[\because \] Units digit of number = 2, so 901352 is divisible by 2. (ii) Divisibility by 3 Sum of digits of given number = 9 + 0 + 1 + 3 + 5 + 2 = 20 \[\because \] 20 is not divisible by 3, so 901352 is not divisible by 3. Now, we see that 901352 is divisible by 2 but not divisible by 3. Hence, it is not divisible by 6. (f) We have, 438750 (i) Divisibility by 2 \[\because \] Units digit of number = 0, so 438750 is divisible by 2. (ii) Divisibility by 3 Sum of digits of given number = 4 + 3 + 8 + 7 + 5 + 0 = 27 \[\because \] 27 is divisible by 3, so 438750 is divisible by 3. Now, we see that 438750 is divisible by 2 and 3 both. Hence, it is divisible by 6. (g) We have, 1790184 (i) Divisibility by 2 \[\because \]Units digit of number = 4, so 1790184 is divisible by 2. (ii) Divisibility by 3 Sum of digits of given number = 1 + 7 + 9 + 0 + 1 + 8 + 4 = 30 \[\because \] 30 is divisible by 3, so 1790184 is divisible by 3. Now, we see that 1790184 is divisible by 2 and 3 both. Hence, it is divisible by 6. (h) We have, 12583 (i) Divisibility by 2 \[\because \] Units digit of number = 3 which is not any of the digits 0, 2, 4, 6 or 8. \[\therefore \] 12583 is not divisible by 2. Now, we have no need to check the given number is divisible by 3 or not because it is not divisible by one of the factors of 6. Hence, the given number 12583 it not divisible by 6. (i) We have, 639210 (i) Divisibility by 2 \[\because \] Units digit number = 0, so 639210 is divisible by 2. (ii) Divisibility by 3 Sum of digits of given number = 6 + 3 + 9 + 2 + 1 + 0 = 21 \[\because \] 21 is divisible by 3, so 639210 is divisible by 3. Now, we see that 639210 is divisible by 2 and 3 both. Hence, it is divisible by 6. (j) We have, 17852 (i) Divisibility by 2 Units digit of number = 2, so 17852 is divisible by 2. (ii) Divisibility by 3 Sum of digits of given number = 1 + 7 + 8 + 5 + 2 = 23 \[\because \] 23 is not divisible by 3, so 17852 is not divisible by 3. Now, we see that 17852 is divisible by 2 but not divisible by 3. Hence, it is not divisible by 6.


You need to login to perform this action.
You will be redirected in 3 sec spinner