## Math Story : Addition and subtraction rules of negative numbers

#### The Negative Bomb Attack – Part 2

“Do not worry! I will not let anything happen to Triho,” says Uncle Math. he musters all the courage and decides to find out which of his parts are injured. He replaces the injured parts with new ones. Immediately they see him move his eyes. “Umm…” he says. Uncle Math and the kids are relieved seeing Triho come out of danger.

“But there must be a way to deactivate these negative number bombs,” says Squarho. “Yes definitely. We can nullify these negative number bombs by using a positive number bomb of equal value. For example, the -8 number bomb can be cancelled using +8 number bomb,” says Uncle Math.

Soon, the news of Triho getting back to consciousness spreads in the enemies’ camps too. “You fool! Why did you leave him like that on the ground? You should have finished him. Enough of your dumbness. I will only have to enter the battlefield now. ” says Uncle Bad.

Uncle Bad is standing in front of a spacecraft. It is not his usual spacecraft. Is he planning to attack through this? What is so special about it? “When the number bombs from this fall on them, they will run to save themselves. But will not be safe. Haha! I am Uncle Bad. I make everyone sad,” he says.

“We will not let anything happen to our planet. This is our home and nobody can steal it from us,” says Triho to motivate his friends. It is a do or dies situation for them.

Both sides are ready today. Who will win? Will the battle end today?

Uncle bad continues to attack. He throws number bombs with -6, -23 and -12. Can you help the kids pick the right number of bombs to nullify the bombs?

Cirha picks the +6 bomb to nullify the -6 number bomb. Squarho picks the +12 bomb to nullify the negative bomb. “There is only a bomb with number 23 here. The +23 bomb is missing. What do I do?” asks Cirho.

“By default, the sign of a number is always positive. So 23 and +23 is the same,” says Uncle Math. Cirho quickly grabs the bomb with 23 and nullifies the -23 bomb. The kids are doing great. But their bombs are getting over too.

Seeing the kids face him bravely, Uncle Bad decides to try a trick. He knows that the kids are left with a few number bombs. So he attacks them with a -10 number bomb. “Oh no! We do not have a +10 bomb to deactivate. What do we do now?” says Cirha. The kids panic.

“No fear when I am here. We can add two numbers to deactivate this -10 bomb,” says Uncle Math. “But how? We have only these negative and positive bombs left. How can we add a negative number with a positive number?” asks Triho. The kids are confused.

“When we add a negative number with a positive number, we find their difference and use the sign of the larger value in the answer. For example: When I add +15 and -5. The answer will be +10 as we use the sign of the greater number.

The kids now understand and attack Uncle Bad with the +15 and -5 number bomb. Boom! His -10 bomb gets deactivated. The kids are elated. Uncle bad does not give up. He now attacks them with a -4 bomb. Can you help the kids to add two bombs to deactivate this bomb?

“We can deactivate -4 bomb by adding 8 and -4 bomb,” says Cirho. Uncle Math agrees with him. The kids are smart and quick learners. Boom! Uncle Bad’s -4 bomb is deactivated successfully. The kids are elated.

“Arggh! How are they doing this? I will throw a +14 bomb this time. They will not be able to deactivate it. Haha!” says Uncle bad and attack them again. “+14? Which bomb do we use now?” says Squarho. “We have -8 and +6 bombs left. When we add them we get -2. We cannot use these,” says Triho. What will they do now? Does Uncle Math have a solution?

“No fear when I am here. We will subtract this time,” says Uncle Math. “Subtract? How?” says Cirho. The kids are confused. “Whenever we subtract a negative number from a positive number, we change the sign to minus and add their values. The result has the sign of the larger number,” explains Uncle Math.

“-8 and -6 give us -14. Hurrah! We can deactivate Uncle bad’s bomb now,” says Cirha. Boom! Uncle Bad’s +14 bomb is cancelled using the -14 bomb. The kids are elated.

Uncle Bad is shocked to see this. His last bomb is deactivated too. What will he do now? Taking advantage of this situation, Triho and his friends attack him with their laser guns. Facing one enemy is easy, but facing 4 of them together is not. Will Uncle Bad accept defeat this time?

The powerful laser rays destroy Uncle Bad’s spacecraft making him fall on the ground.

Seeing his enemies overpower him, Uncle Bad has no other option than to surrender. “Leave me! Don’t punish me. I promise to never come back,” he pleads. “He always breaks his promise. How can we trust him?” says Squarho furiously. Should the kids leave Uncle Bad? Should they punish him?

“We will let you go but only on one condition. You need to hand over all your gadgets, weapons and spacecraft to us. You also will go far and very far from Earth that you can never come back,” says Triho. All the friends are proud of Triho’s decision.

Uncle bad does as asked to. He then runs fast, faster and faster to save himself.

“Hurrah! Finally, we did it,” says Cirha. All of them hug each other. “You all are great! Having learnt all the math concepts helped you fight Uncle Bad bravely. You have saved the entire planet. I do not have words to thank you all,” says Uncle Math emotionally.

“We could do this only because we had a great teacher like you, Uncle Math. You are the best,” say the kids together. They hug him. Finally, it is time for a grand celebration. Samper town is out of danger. The citizens can now live in peace.

Education always helps us fight our enemies and face our fears. Triho and the kids successfully fought their enemies and faced their fears. Are you ready to face yours?

We Learnt That…

• By default, the sign of a number is always positive.
• When we add a negative number with a positive number, we find their difference and use the sign of the larger value in the answer.
• Whenever we subtract a negative number from a positive number, we change the sign to minus and add their values. The result has the sign of a larger number.
• Education always helps us fight our enemies and face our fears.

Let’s Discuss

• How did Uncle Math help Triho?
• How did we deactivate the bombs?
• Explain the rules to add and subtract negative numbers.
• “Education always helps us fight our enemies and face our fears.” Do you agree? Why or why not?