What is the place value of 7 in 3.487?

The number is 3.487.

• 3 is in the ones place.
• 4 is in the tenths place ($\frac{4}{10}$).
• 8 is in the hundredths place ($\frac{8}{100}$).
• 7 is in the thousandths place ($\frac{7}{1000}$).

The place value of 7 is $\frac{7}{1000}$.
The correct option is A.

3. Find the highest common factor (H.C.F) of 4, 6 and 12.

Factors of 4: 1, 2, 4
Factors of 6: 1, 2, 3, 6
Factors of 12: 1, 2, 3, 4, 6, 12

The common factors are 1 and 2.

The highest common factor (H.C.F.) is 2.
The correct option is A.

4. Which of the following is not a multiple of 3?

A. $6 \div 3 = 2$ (6 is a multiple of 3)
B. $9 \div 3 = 3$ (9 is a multiple of 3)
C. $16 \div 3 = 5$ with a remainder of 1 (16 is not a multiple of 3)
D. $12 \div 3 = 4$ (12 is a multiple of 3)
E. $24 \div 3 = 8$ (24 is a multiple of 3)

16 is not a multiple of 3.
The correct option is C.

5. Find the square root of $3^2 \times 4^2$.

The correct option is B.

6. Find the difference between the sum of 128, 857, 155 and 140.

Given the options, this question is best interpreted as finding the difference between the sum of the first three numbers and the last number.
Sum of 128, 857, and 155:

The correct option is B.

7. Divide the L.C.M. of 9, 12 and 18 by their H.C.F.

Prime factorization:
$9 = 3^2$
$12 = 2^2 \times 3$
$18 = 2 \times 3^2$
L.C.M. is the product of the highest powers of all prime factors: $2^2 \times 3^2 = 4 \times 9 = 36$.

H.C.F. is the product of the lowest powers of common prime factors: $3^1 = 3$.

by the H.C.F.

The correct option is D.

8. Express $\frac{144}{256}$ in its lowest term.

We can simplify by dividing by common factors repeatedly.

The numbers 9 and 16 have no common factors other than 1.
The fraction in its lowest term is $\frac{9}{16}$.
The correct option is A.