Math Story : Addition And Subtraction On Number Line
Uncle Math And His Gadget
Cirha and Cirho : Uncle Math, Acirho has stolen our candies, and we are left with only one candy now.
Uncle Math : Oh no! Do not worry kids. I will give both of you the same number of candies you had. How many candies did you both have in total?
Cirha : 1…2…5…oh! This is so confusing, Uncle Math. Can you help us?
Uncle Math : Sure dear! No fear, when I am here! I have this amazing number line gadget to help you.
Cirho : Wow! What is this Uncle Math?
Uncle Math : A number line makes addition or subtraction easy and will help you find the number of candies Acirho had stolen.
Cirho : Wow! Thank you Uncle Math.
Cirha : How do we use this, Uncle Math?
Uncle Math : As you go right on the number line, numbers increase and as you go left, the numbers decrease.
Cirho and Cirha : Wow!
Uncle Math : For example, I had 3 apples and I bought 4 more apples, then I can use a number line to find the total apples. I would simply search for the number 3 on the number line. Encircle number 3 and stand here.
Uncle Math : Since I bought 4 more apples, I would jump forward four times towards the right on the number line from the number 3. The number at which I end up would be the number of total apples with me. Can you tell which operation we used here to find the total number of apples?
Cirho : Addition.
Uncle Math : Correct, Cirho! So here, 3 + 4 = 7.
Uncle Math : Okay, coming back to your problem, now tell me how many candies you had, Cirha?
Cirha : I had 2 candies.
Uncle Math : Okay! Go stand at 2 and encircle it. How many candies did you have, Cirho?
Cirho : I had 3 candies.
Uncle Math : Okay tell me Cirho how many times should Cirha jump to find out the total number of candies with both of you?
Cirho : As I had 3 candies, she should jump forward three times, on the right.
Uncle Math : Correct! Cirho.
Cirha : 1…2…3.
Uncle Math : Can you tell me the total number of candies with both of you?
Cirha and Cirho : 5 candies.
Uncle Math : You both are absolutely correct.
Cirha and Cirho : Yaaay!
Cirha : But Uncle Math, how will we find out the number of candies stolen by Acirho from us?
Uncle Math : So you both are left with one candy, right? Cirho and Cirha : Yes.
Uncle Math : Okay, here we need to subtract. For subtraction, we jump backwards on the left on the number line. Cirha, just jump one step back towards the left.
Cirha : 1…
Uncle Math : So, five minus one gives us four. Now, do you get it? How many candies did Acirho steal?
Cirho and Cirha : Yes, four candies!
Uncle Math : Correct answer! As promised, I will give four candies to both of you.
Uncle Math : Here you go, four candies.
Cirho and Cirha : Hurray! Thank you, for the candies Uncle Math.