Mental Math - Class 4

•  

  What is a greater distance, 10 cm or 10 m?

• 10 cm

• 10 m

Answer explanation

The greater distance is 10m because meters are a larger unit of measurement compared to centimeters. Therefore, 10 meters is a greater distance than 10 centimeters.

If you add 9 to this number, you get 81. What’s the number?

• 63

• 9

• 72

• 27

Answer explanation

Adding 9 to the number 72 results in 81

• 
  You walk into a room with a match. In the room, there is a stove, a heater, and a candle. What do you light first?

• Heater

• Stove

• Candle

• Match

Answer explanation

The correct answer is to light the match first. This is because a match is needed to ignite both the stove and the candle. The heater does not require a match to be lit as it is typically powered by electricity or gas. Therefore, the match is the logical item to light first in order to proceed with lighting the other objects in the room.

How many tens are equal to one thousand?

• 10

• 100

• 1000

• 10000

Answer explanation

One thousand is equal to 100 tens.

If you multiply this number by any other number, the answer will always be the same. What number is this?

• 0

• 1

• 10

• 100

Answer explanation

When you multiply any number by 0, the product will always be 0. This is because any number multiplied by 0 equals 0. Therefore, 0 is the only number that satisfies the condition mentioned in the question, making it the correct answer.

What is 1/3 of 21?

• 5

• 6

• 7

• 8

Answer explanation

To find 1/3 of 21, we can divide 21 by 3. When we divide 21 by 3, we get a quotient of 7. Therefore, 1/3 of 21 is equal to 7.

Write down two numbers with a sum of 9 and a difference of 1.

• 7, 8

• 11, 12

• 4, 5

• 2, 3

Answer explanation

The two numbers that have a sum of 9 and a difference of 1 are 4 and 5. When you add 4 and 5, you get 9. And when you subtract 4 from 5, you get 1. Therefore, the numbers 4 and 5 satisfy the given conditions.

• 
  How can you add eight 4’s together so that the total adds up to 500?

• 4+4+4+4+4+4+4+4

• 4+4+4+44+444

• 44+44+44+44

• 4+44+444+44

Answer explanation

4+4+4+44+444 is the correct answer

What can you put between 6 and 9, so that the result is greater than a 6 and smaller than 9? (Hint: Use any mathematical symbol)

• 6+9

• 6x9

• 6-9

• 6.9

Answer explanation

By inserting a decimal point between 6 and 9, the resulting number becomes 6.9. This number is greater than 6 but smaller than 9.

What will be 23:40 in 12-hour time?

• 11:40pm

• 11:40am

Answer explanation

The given question asks for the 12-hour time equivalent of 23:40. In the 12-hour time format, the hours range from 1 to 12, so any time after 12:00 is converted by subtracting 12 hours. Therefore, 23:40 is equivalent to 11:40pm in the 12-hour time format.