Fun With Rounding

Topic: Round Numbers To Nearest Tens

It is a beautiful day. Uncle Math is enjoying working on his new research project. The kids are also performing some experiments with him.

Suddenly, Mr Messenger comes running. It looks like he has received a new message. What do you think this might mean? “Madam Word has been trapped by Atriho Boss. He has taken her to Rounding Planet and is hiding there”, announces Mr Messenger sadly. Hearing this, Uncle Math panics. The kids are worried too.

“Without wasting time, let us immediately leave for the Rounding Planet”, suggests Triho. Everybody agrees.

They immediately board their spacecraft and leave. Anxious, worried, will they really find Madam Word and save her?

Soon, they reach the Rounding Planet. “Ahhh!” They hear some loud screams. “That must be Madam Word, let us follow the sound. I am sure we’ll find her”, says Cirha. They immediately rush to find her.

As they move ahead, they spot a weird ride, that has many numbers on it. “Look there! Atriho Boss is running away”, says Squarho.

Triho touches the ride and suddenly hears a mysterious voice. “I am the ‘Rounding Coaster’. You will have to board me to reach the other side”, announces the mysterious voice.

Left with no other choice, everybody boards the Rounding Coaster. Everybody takes their positions on different numbers. Cirho sits at 3, Cirha at 7, Triho at 10, Squarho at 15 and Uncle Math at 20. Will the ride really take them to Atriho Boss?

Thudd! The ride begins. Initially, it moves straight. “Oh! This is so easy, we were fearing for no reason”, says Cirho. But, if this was so easy, Atriho Boss wouldn’t have come here right? Do you really agree with Cirho?

Soon, the ride changes its pace. Suddenly it starts getting up and down like a wave at certain places. “Oh no! This is so scary”, screams Cirha. “I am going to fall”, screams Cirho. What will they do now? Will they be able to reach the other side of the ride safely?

“Oh yes! I am sliding towards the end of the ride”, screams Squarho. Triho is stable at 10. Uncle Math reaches the end of the Rounding Coaster.

Squarho also reaches the end of the ride.

Cirho, Cirha and Triho are clueless. But soon, Cirho jumps on the number 16. Triho and Cirha jump on the number 18 and number 19 respectively.

Again, the ride changes its pace. It starts getting up and down. Cirho, Triho and Cirha are sliding towards the end of the Rounding Coaster.

Finally, the ride stops. Everybody is safe. “I am impressed, you can now walk to the other end safely”, announces the Rounding Coaster. Everybody is relieved.

“Why is it called the ‘Rounding Coaster’?” asks Cirha. “Rounding off means a number is made simpler by changing it to its nearest approximate number. The Rounding Coaster is using rounding off to the nearest tens. That’s why it is called Rounding Coaster”, explains Uncle Math.

Cirha is still clueless. Uncle Math decides to explain further. “Whenever we round numbers to the nearest tens, we check the digit in ones place and jump to the nearest tens. For example, Cirho was at 3. The nearest ten to 3 is the number 0. So he reached number 0. Since Cirho came down to a smaller number here, this is nothing but, rounding down”, explains Uncle Math.

“Why 0 only? Why not 10?” asks Triho. “If Cirho had to go to number 0, he had to just take 3 steps back, whereas if he had to go to number 10, he would have taken 7 steps ahead. Clearly, moving to 0 was more efficient here”, explains Uncle Math.

“Oh right! That means for Cirha, moving to 0 would have been a bad idea, as number 10 was closer to number 7 than number 0”, says Triho. “Since Cirha was moving ahead to reach 10, this will be called rounding up”, adds Uncle Math.

“But when Squarho was sitting on 15, he directly reached the end of the Rounding Coaster. Why? Both 10 and 20 were at an equal distance”, asks Triho.

“Good question. In such a case, Rounding Coaster chose the higher number, which was 20 in this case”, says Uncle Math. Triho is all clear now.

“Oh no! I cannot spot Madam Word or Atriho Boss! What do we do now?” says Cirha worriedly. “Save me!” suddenly they hear a scream and decide to follow it.

Soon, they spot Atriho Boss forcefully holding Madam Word. “Attack them!” he orders his gang members. Triho and Squarho fight the bad robots bravely.

Uncle Math, Cirha, and Cirho manage to reach Atriho Boss. Together, they attack him. Seeing 3 of them attacking, Atriho Boss runs to save himself. “I will not leave you! I will come and trouble you again”, he screams while running.

Madam Word is finally relieved. “Thank you so much for saving me”, she says. Everybody is glad to have saved her. It’s time to head back home now. A big rescue challenge, Rounding Coaster and its mystery, and a day filled with learnings, indeed a purposeful day!

We Learnt That…

  • Rounding numbers means approximating the digits (up or down) to make rough calculations easier.
  • Whenever we round the numbers, we use the words like ap proximately, almost and about.
  • We round up when the digit in one’s place is greater than or equal to 5.
  • We round down whenever the digit in one’s place is less than 5.

Let’s Discuss!

  • Where were we going today? Why?
  • What is rounding numbers to the nearest tens?
  • Explain rounding up with an example.
  • Explain rounding down with an example.