Math Story : Order Property Of Subtraction

The Tank Mystery

Acirho Boss and his gang are coming to Samper Town. But why? Why can’t they let people live in peace?

“You are dead this time”, says evil Acirho Boss. “What do we do now?” worries Cirho. The kids and Uncle Math are thinking of various ways to tackle the villain. “No fear when I am here”, says Uncle Math. He leaves to get something. Is he getting a new gadget?

Uncle Math is back with a huge machine. “Hurry up! Acirho Boss is very close. Board the tanker”, he says. Everybody follows his instruction.

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“You have to insert these balls into this tanker to throw them at the boss villain”, says Uncle Math hurryingly. Suddenly, one of the bombs of Acirhos hits the nearby house. Boom! It destroys the house.

Everybody is scared. “Cirho, Squarho! Join me. Let us stop the Acirhos. Cirha and Triho you go and stop Acirho Boss. Go!” guides Uncle Math. Immediately, everybody gets into action.

On one side, Uncle Math, Squarho and Cirho are fighting bravely. On the other side, Triho and Cirha are chasing the boss villain. Will they be able to stop them?

Cirha and Triho are close to Acirho Boss now. They decide to attack him with the balls now. There are two pipes to insert balls into the tanker. Immediately, Triho inserts 8 balls into one pipe and Cirha inserts 3 balls into the other.

 “Aiming 5 balls”, the tanker announces. “5? We put 8 + 3 balls. The tanker must be aiming 13 balls in total, but why is it throwing only 5?” asks confused Cirha.

The 5 balls hit Acirho Boss’s tanker. He looks worried now. Cirha and Triho continue inserting more balls into the tanker. This time they put 10 and 4 balls. “Aiming 6 balls”, announces the tanker. The throw is great, but the kids are confused with the tanker.

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Uncle Math 6 to 8 Years App Banner

Trying to understand the mystery behind the tanker and the balls, suddenly, Triho starts smiling. “I know what is the tanker doing. When we put 8 and 3 balls, it threw 5 balls. When we put 10 and 4, it threw 6.  That means the tanker is actually, subtracting the balls and aiming them at Acirhos”, he says.

“Oh yes! So this is a subtraction tanker. You are a genius”, says Cirha. They continue inserting more balls and attacking the villains. Bam! The balls blow off some of the gang members protecting the boss. This frustrates Acirho Boss and he aims some balls at them. Some hit Triho and he is injured. Cirha cannot take this and decides to use the tanker to attack.

She inserts 4 balls in the first pipe and 10 in the other. Thinking, the tanker will aim 6 balls now, she is happy. But something strange happens. “Not possible!” announces the Tanker. She is confused. But Acirho Boss is really close to them. What will she do now?

Uncle Math comes to her rescue. He re-enters 10 in the green column and 4 in the red. “Aiming 6 yellow balls”, announces the tanker. Bam! Acirho Boss is injured. He cannot move.

Hurray! The kids and Uncle Math saved the town once again. Triho is feeling better. 

“But why didn’t it work when I reversed the order i.e 4 in the first pipe and 10 in the other?” asks curious Cirha. 

“How can you subtract a bigger number from a smaller number Cirha? 10 is greater than 4. You were subtracting 10 from 4. That is why it did not work. Whenever we subtract we should always keep in mind the order in which the numbers are placed”, explains Uncle Math.

“Unlike addition, where even after exchanging the order of the numbers, the result does not change. But In subtraction, exchanging the order of numbers does affect the result. Thus we should stick to a particular order”, adds Uncle Math.

“Oh! This is so important and tricky”, says Cirha. The kids have understood now. Everybody helps Triho to head back home. Whoever the villain may be, teamwork and Uncle Math’s genius gadgets always are going to help Samper Town.

We Learnt That…

  • Exchanging the order of numbers does not change the result when we add the numbers.
  • Exchanging the order of numbers does change the result when we subtract the numbers.
  • With teamwork, we can face any problem.

Let’s Discuss

  • Who was attacking the town?
  • How did Triho and Cirha understand the tanker mystery?
  • How did we save the town using the Subtraction tanker?
  • Can we exchange the order of numbers while subtracting? Why or why not?

Use this guide by Fun2Do Labs for teaching properties of subtraction to kids :