Practice adding and subtracting within 20 using a Double 10-frame & number line. Represent a teen number using a number bond to solve a Mystery Math Mistake. Use Notice and Wonder with a marble game ...

You can subtract in Excel by placing a minus sign in front of any numbers you want to deduct. You can add and subtract a bunch of numbers at once using the equal sign or SUM function. You can add and ...

Take this quiz to see how much you know about this topic already, then work through the guide and see if you can beat your score. Take a look at this number line. It shows 14 - 5 = 9. You can count ...

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