# Decimal Numbers Quiz Set 001

### Question 1

What is \${0.40 × 0.40 × 0.40 + 0.05 × 0.05 × 0.05}/{2.00 × 2.00 × 2.00 + 0.25 × 0.25 × 0.25}\$?

A

\$1/5^3\$.

B

\$1/5^2\$.

C

\$1/5\$.

D

\$1/5^4\$.

Soln.
Ans: a

By inspection, the given ratio is same as \${0.40 × 0.40 × 0.40 + 0.05 × 0.05 × 0.05}/{5^3 × ({0.40 × 0.40 × 0.40 + 0.05 × 0.05 × 0.05})}\$ which is \$1/5^3\$.

### Question 2

What is \$18{54/10000}\$?

A

18.0054.

B

18.054.

C

18.00054.

D

18.54.

Soln.
Ans: a

The given expression can be written as \${18 × 10000 + 54}/10000\$ which is same as \$180054/10000\$ which gives 18.0054

### Question 3

For what value of x would this expression be a perfect square: \$6.16 × 6.16 - x × 6.16 + 0.3 × 0.3\$?

A

0.6.

B

0.06.

C

0.0006.

D

6.0.

Soln.
Ans: a

Comparing the given expression with \$a^2 - 2 × a ×b + b^2 = (a - b)^2\$, we see that if a = 6.16, and b = 0.3 then by inspection, x should be equal to 2b = 2 × 0.3 = 0.6.

### Question 4

What is \${(-63) × 2.5 - 95 × (-6.3)}/6.4\$?

A

\$68{29/32}\$.

B

\$68{27/32}\$.

C

\$68{31/32}\$.

D

\$68{28/32}\$.

Soln.
Ans: a

Observe that all fractional numbers are having one digit to the right of the dot. So we can cancel all the dots and get a plain expression: \${(-63) × 25 - 95 × (-63)}/64\$. We can now simpilfy the minus signs to get \${(95 × 63) - (63 × 25)}/64\$ which equals \${2205/32}\$, which is same as: \$68{29/32}\$

### Question 5

What is \$6.845 - (-0.1) + 0.04 - (-0.08)\$?

A

7.065.

B

8.065.

C

6.065.

D

9.065.

Soln.
Ans: a

The given expression is same as \$6.845 + 0.1 + 0.04 + 0.08\$, then by simple addition we get \$6.845 + 0.1 + 0.04 + 0.08 = 7.065\$. 