Numbers
Q. 1 If 60% of 3/5 of a number is 36, then the number is:Answer: Let the number be x
Then 60% of 3/5 of x = 36,
60/100 *3/5*x = 36,
x = 36 *25/9 =100
Required number is 100.
Q. 2 The difference between the local value and the face value of 7 in the numeral 32675149 is
Answer:
Local value of 7 - face value of 7 = 70000 - 7 = 69993.
Q. 3 The unit digit in the product (784*618*917*463) is
Answer :The unit digit in the given product = unit digit in (4 *8*7*3 =672)=last digit is unit digit =2.
Q.4 How many prime numbers are less than 50?
Answer:
prime numbers are less than 50 are: 2,3,5,7,11,13,17,19,23,29,31,37,41,43,47.
Their Number is 15.
Q. 5 If the number 91876*2 is completely divisible by 8, then the smallest whole number in place of * will be:
Answer:
The number 6x2 must be divisible by 8.
If x=3 then 632 is divisible by 8.
Hence,* = 3
Q. 6 On dividing a number by 357, we get 39 as remainder. On dividing the same number by 17,what will the remainder?
Answer:
Let x be the number and y be the quotient Then,
x = 357 * y + 39
= (17*21*y) +(17*2)+5
= 17 * (21 y +2)+5
Required Remainder =5.
Q. 7 In a division sum, the remainder is 0. A student mistook the divisor by 12 instead of 21 and obtained 35 as quotient. What is the correct quotient?
Answer:
Number = 12 * 35 =420
Correct quotient = 420/21 =20.
Q. 8 How many natural numbers are there between 23 and 100 which are exactly divisible by 6.
Answer:
Required numbers are 24,30,36,42,...,96
Where, a= 24, d = 6,tn =96
We know that,
tn = a+ (n-1) d
96 = 24 +(n-1)6
12 = (n-1)
n = 13.
Their are 13 natural numbers.
Q. 9 The sum of first five prime number is :
Answer:
Required sum = ( 2+3+5+7+11) = 28.
Q. 10 The least number which can be subtracted from 100 so that it is completely divisible by 7:
Answer:
When 100 is divided by 7 then remainder is 2
Hence, The least number is 2.
Consider the remainder for subtraction.
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