Archive for the ‘subtraction’ Category

What is the best way to teach addition and subtraction to a 1st grader?

Friday, January 22nd, 2010

We have tons of homework every night. I do not mind passing it down. That is what it is all about. However, I truly do not remember how I learned to add and subtract. Funny, I know. I do remember MEMORIZING my Multiplication and Division Tables. So… I showed him with pennies, and then we did it with fingers, and then we wrote it down….then we said it over and over and over 5 times each….??????? Thx. ;)
The most important things to remember are that kids need to be taught in a variety of ways and they need repetition. If your child does not have a concept of what a 5 actually is… then adding 5 plus 5 means nothing to him. Keep using objects, fingers, ruler, hundred chart, number line etc. You can go online for printable games and online games. You can visit your local teacher supply store for flashcards and board games. (My students also like to use addition Wrap Ups). Teach him to always start with the biggest number and add up. Example: 8+2 "Which number is the biggest? Find the 8 on your ruler and count up 2".

It may help for him to know the cumulative property, the concept that 8+2 has the same answer as 2+8. When doing an addition worksheet, I have kids do the first problem, then go on a search to find other problems they can "cheat" on. It’s great that you are willing to take the time to help him with his homework; all kids should be so lucky.

How can i make the number 8,8,3,3 equal 24 using additon, subtraction, division, and multiplication?

Friday, December 11th, 2009

you can use additon, subtraction, division, and multiplication as many times as you want but you can only use the numbers once.
you have to use 8,8,3,3 all but only once

like…
8*8*3*3

could it be 8 * 8 / 3 +3?
8 * 8 / 3 +3 = 64 / 3 +3= 21,3 +3 = 24,3

How do I teach subtraction with regrouping of zeros?

Tuesday, December 1st, 2009

My little brother came up to me and asked for help in his math homework. His problem is $100.00 - 55.99 the answer is 44.01 but he wanted to explain why. How can I explain regrouping with multiple zeros’ to him instead of just saying, " That’s the way it is?" My little brother is in third grade.

have him do 23 minus 7 with crackers.

use small goldfish for the ones, and saltines for the tens.

So he gets 2 saltines and 3 fish. As soon as you tell him the saltine is worth 10 fish - he will see that he can borrow by "trading it in" to you - so he can subtract 7 from his grouping.

He should then be able to see why you have to borrow from each spot. look up more on place value if you want to find some other activities for his level.

Explain how you know to use a variable in an addition or subtraction expression?

Tuesday, November 24th, 2009

Explian how you know to use a variable in an addition or subtraction expression?

Give an example.

For example, if you have 10x + 6x it equals 16x.

If you have 10x - 6x it equals 4x.

What you cannot do is add or subtract different variables such as 10x - 4y. That stays 10x - 4y.

I don’t know if that answers your question.

what is the best book to help my 1’st grader understand subtraction?

Friday, November 20th, 2009

My daughter is in first grade and is struggling in Math already. She especially can’t understand subtraction. I’ve tried so many different ways. I think they just teach so fast and move on to the next problem too quickly for her. Any tips from other parents on what to do?

Maybe try visually, have ten straws give her 10, then take away 5 and ask her how many does she have left? Every time she gets it correct she gets a point. 3 points equals a cookie or whatever.

What is the number that is being subtracted in a subtraction problem called?

Monday, November 16th, 2009


Minuend The number being subtracted from the subtrahend.

Subtrahend The number being subtracted.

Sum The answer in an addition problem.

What program can perform pixel subtraction between 2 similar images to show the differences?

Saturday, November 7th, 2009


You can do this in photoshop - just load each image into separate layers, and make the blending mode "difference".

how do you answer this question about subtraction?

Monday, October 26th, 2009

Your second grade sister is learning about subtraction and she says to you: "When you subtract, you always take the smaller number away from the larger number." Based on what you have learned about subtracting integers, explain why your sister’s statement is not always true. Write a problem that supports your written explanation.

It is not always true because answers can be in negative integers, for example,

5 - 8 = -3 we are subtracting a larger nmber from a smaller one.

how do you answer this question about subtraction?

Monday, October 26th, 2009

Your second grade sister is learning about subtraction and she says to you: "When you subtract, you always take the smaller number away from the larger number." Based on what you have learned about subtracting integers, explain why your sister’s statement is not always true. Write a problem that supports your written explanation.

It is not always true because answers can be in negative integers, for example,

5 - 8 = -3 we are subtracting a larger nmber from a smaller one.

Would I write the addition and subtraction in the same algorithm or use branching?

Saturday, October 24th, 2009

Suppose you are asked to design a software tool that helps an elementary school student learn
arithmetic operations. The software allows the student to select the arithmetic operation she or he
wishes to study. The student chooses from a menu one of five arithmetic operations: 1) addition,
2) subtraction,(other arithmetic operations have not been include to keep the problem simple).
Based on the student choice, the software tests the user with exactly 10 questions. For each
question, two random positive one-digit integers are generated; then the student is asked to enter
the answer for the arithmetic operation applied to the two numbers.

The software displays a message “Congratulations!” if more that 7 questions are answered
correctly, otherwise, the program should display "Please ask your teacher for help".

What I would do after getting the input from the user as to what operator they want to use, and checking that the input is valid, is:

- do a loop of 10 for each of the 10 questions.
- - get the 2 random numbers.
- - then do a switch on the inputted operator.
- - - according to which operator, generate the answer.
- - - ask the user to answer.
- - - compare the users answer to the generated answer.
- - - update the amount of correct answers if it is correct.
- - end switch.
- end loop.

OR

- do a loop of 10 for each of the 10 questions.
- - get the 2 random numbers.
- - then do a switch on the inputted operator.
- - - according to which operator, generate the answer.
- - end switch.
- - ask the user to answer.
- - compare the users answer to the generated answer.
- - update the amount of correct answers if it is correct.
- end loop.

Then check the amount of correct answers to output the message of congratualtions or not.

Good luck with it.