Subtraction games that teach:
Subtract equations up to 3 digits and powers of up to 10, 100, 1000.
Can your child subtract 3 digit numbers?
By 4th grade children should have no problem solving equations like this: 235-139. If they truly understand the number system they might solve it like this:
1. I know that 139 plus 100 is 239...and that is 4 more than 125 so... I take 100 and subtract 4 for 96.
2. If I count backwards by 10's from 235 I get 90 then count up 6 ones for a total of 96.
3. 200-100 is 100 and 39-35 is 4....100-4=96
Using a number chart or number line is more than ok!
There are a million ways to solve the problem, the key is that your child is comfortable enough with the number system and can use a logical strategy to find the answer (the whole point of playing these subtraction games).
If they are not there yet...do not worry, they simply need more exposure to hundreds and/or thousands charts AND of course, more subtraction games.
The following subtraction games and activities will help your child get a good handle on the number system:
Start off by practicing counting forward and backward to and from 1000. Count by 1's, 10's, 100's, and 1000's forward and backwards.
Crazy Math Mom Tip: I call the process of counting forward and backward by 1's, 2's,5's, etc. a "warm up", just like a warm up before you exercise. You have to stretch out your "Math Muscles". Before you begin homework or play subtraction games, you can stretch out your "Math Muscles".
Here are some ideas adapted from letsplaymath.net-
(1) Think of the hundred chart as a number line (you can even use one row to add and subtract small numbers). The chart can support your child while you ask difficult addition and subtraction problems. Take turns making up problems for each other to solve.
Print off a 100 chart and Try these:
Try adding and subtracting by tens first (counting up or down) then the ones (counting left or right.) If your in the car use numbers you spot on the road as a starting spot- it makes the activity much more engaging.
For example, if I see a speed limit sign, 60 mph I start with 60. On the hundreds chart I mark 60 visually then make up a problem like subtract 10, then 5, then 3...what is the answer?
(2) Look for addition and subtraction patterns. 3+7=? Now go to 43+7, 73+7, 83+7. What do you notice? What do 10-7, 20-7, 30-7, etc. have in common? What other patterns can you make? Kids are amazed when they see these patterns.
(3) Make a puzzle with the chart, cut in up into pieces and have your child put it back together.
(4) Cover up numbers( use sticky notes or dots) on the chart and see if your child knows which numbers are covered up!
(5) We love to play games with arrows, for example start at 71, go back 2(← ←), go right 1(→), then up 1(↑), what number do you have? My kids love to make up arrows for me.
(6) Count by 25's (think of quarters), 10 (think of dimes), 1 (think of pennies), 100 (think of dollars). Drive-thru: You can even use the 100chart to subtract things- when we go through the drive-thru I will tell them we have a certain amount of money to spend. I have them get out their hundreds chart and subtract the price of each item(we round the numbers) and see if we will have enough money. It is a great way to spend time waiting for your food.
If you were like me you probably look at some of the math your child brings home and say to yourself, "I learned how to subtract the old fashion way by borrowing numbers, and that worked out for me. Why does my child have to learn this way?" The short answer is that if your child can mentally add larger numbers then, later on it will pay off ten fold. It will help in long division, algebra, etc. You must just trust that is vitally important to help your child mentally subtract.