Writing a Number as a Product of Its Primes

Q. Find a number between 800 and 900 which is divisible by 22, 33, and 66.

Q.

Which of the following is not a prime factorization?

1. $30=3\times 10$

2. $15=3\times 5$

3. $120=2\times 2\times 2\times 15$

4. $18=2\times 3\times 3$

Q.

Express $61$ as the sum of three primes?

Q.

How many times does 5 occur in the factorisation of 1225?

1. 0

2. 1

3. 2

4. 3

Q. 4 is a of 24 and 24 is a of 4.

1. Multiple
2. Remainder
3. Factor
4. Dividend

Q.

Write $1360$ in prime factorisation form.

Q.

If a number is divisible by 2 and 4, it is divisible by 6.

1. True

2. False

Q.

Write all the multiples of $11$ up to $100$.

Q.

Given that 312 is divisible by 26. It will also be divisible by:

1. 4

2. 6

3. 13

4. 3

Q. Express 66 as a product of its primes.

1. $33\times 2$
2. $22\times 3$
3. $6\times 11$
4. $2\times 3\times 11$

Q.

Which among the following pairs of numbers have the same number of factors?

1. $16,81$

2. $2,10$

3. $3,9$

4. $16,20$

Q. Match the following with its prime factors.

1. $2\times 2\times 3\times 5\times 5$
2. $5\times 5\times 5$
3. $3\times 3\times 3\times 3$

Q.

Express $39$ as the sum of three primes?

Q. Write the smallest 4-digit number and express it as a product of primes.

Q.

Factor out the indicated number.

Factor $-8$ out of $(-32d+56)$

Q.

Express $31$ as the sum of three primes?

Q.

Amita has 12 marbles and Reeta has 8 marbles. Reeta says that she has $\frac{x}{y}$ times the marbles that Amita has, where $x$ and $y$ are co-prime numbers.

Then $x+y=$ ___

Q.

Which expression is not equivalent to the expression $?$

$72m-60$

1. $6(12m-10)$

2. $4(18m-15)$

3. $12m$

4. $12(6m-5)$

Q.

Express each of the following as the sum of two primes

$84$

Q.

Express $21$ as the sum of three primes?

Q.

Express $12$ as the sum of two primes?

Q.

Show that the given pair of numbers are co-primes: $15,16$

Q.

How many times does 2 occur in the factorisation of 720?

1. 1

2. 2

3. 3

4. 4

Q.

Which of the following numbers have exactly 12 factors?

1. 610

2. 1220

3. 300

4. 1800

Q. If $A=3\times 5$ and $B=7\times 11$, then how many factors does $A\times B$ have ?

1. 4
2. 1155
3. 2
4. 16

Q.

Express 10 as a product of its primes.

1. 2 x 2

2. 2 x 5

3. 2 x 3

4. 5

Q. Which of the following is a prime number?

(a) 263
(b) 361
(c) 323
(d) 324

Q.

How many times does 2 occur in the factorisation of 154?

1. 0 times

2. once

3. twice

4. thrice

Q.

Question 4

Write the greatest 4-digit number and express it in terms of its prime factors.

Q. If $A=2\times 2\times 2\times 3\times 3$ and $B=2\times 2\times 3$, then how many factors does $\frac{A}{B}$ have?

1. 6
2. 24
3. 4
4. 3