# Decimal Numbers Quiz Set 009

### Question 1

0.00218828 is same as?

A

\$2.18828 × 10^{-3}\$.

B

\$2.18828 × 10^{-2}\$.

C

\$2.18828 × 10^{-1}\$.

D

\$2.18828 × 10^{-4}\$.

Soln.
Ans: a

### Question 2

What is \${(-32) × 2.9 - 47 × (-3.8)}/6.9\$?

A

\$12{10/23}\$.

B

\$12{9/23}\$.

C

\$12{7/23}\$.

D

\$12{11/23}\$.

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: \${(-32) × 29 - 47 × (-38)}/69\$. We can now simpilfy the minus signs to get \${(47 × 38) - (32 × 29)}/69\$ which equals \${286/23}\$, which is same as: \$12{10/23}\$

### Question 3

For what value of x would this expression be a perfect square: \$1.76 × 1.76 + x × 1.76 + 0.5 × 0.5\$?

A

1.

B

0.1.

C

0.01.

D

0.001.

Soln.
Ans: a

Comparing the given expression with \$a^2 + 2 × a ×b + b^2 = (a + b)^2\$, we see that if a = 1.76, and b = 0.5 then by inspection, x should be equal to 2b = 2 × 0.5 = 1.

### Question 4

What is \$0.15966/0.02\$?

A

7.983.

B

6.983.

C

5.983.

D

8.983.

Soln.
Ans: a

The given expression can be written as \${15966/2} × {100/100000}\$ which is same as \${15966/2} × {1/1000}\$, which is same as \$7983 × {1/1000}\$, which is same as 7.983

### Question 5

Which is the smallest?

A

\$0.32^3\$.

B

\$1/0.32\$.

C

\$0.32\$.

D

\$0.32^2\$.

Soln.
Ans: a

We know that if a number is less than 1, then it becomes smaller and smaller as it is raised to higher and higher positive powers. Now, \$1/0.32\$ is same as \$0.32^{-1}\$. The three powers of 0.32 given to us are -1, 1, 2 and 3. Out of these 3 is the most positive, so, \$0.32^3\$ is the smallest. 