Numbers
Practice Questions on Number System
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Q7) For a natural number 'n', 7n2 + 7n is divisible by which of the following? 1) 14 only 2) 7 only 3) 21 only 4) 7 and 14 both 7n2 + 7n = 7n(n + 1) is divisible by 7 and 14 both, as n(n + 1) is always even. Hence, option 4. Q8) Find the largest 4 digit number that is divisible by 7? 1) 9996 2) 9997 3) 9995 4) 9993 Divide 9999(Largest 4 digit number) by 7 and get remainder 'R'. R = 3. ∴ Required number is (9999 - R) = (9999 - 3) = 9996 Hence, Option 1. Q9) Find the units place of 12783571. 1) 2 2) 6 3) 8 4) 4 Unit's digit of 12783571 = Unit's digit of 83571. Remainder when 3571 is divided by 4 is 3. ∴ Unit's digit of 83571 = Unit's digit of 83 i.e. 2 Hence, option 1. Q10) Which of the following numbers is divisible by 8. 1) 123456 2) 241368 3) 234576 4) All of above A number is divisible by 8 if last three digits of a number are divisible by 8. Hence, option 4. Q11) Sum of first 45 natural numbers is 1) 990 2) 2070 3) 900 4) 1035 Required sum  Hence, option 4. |