Mental math with 3-digit numbers (addition and subtraction)

These little puzzles are actually equations with an unknown. Here we use a shape for the missing number. Put your thinking caps on and solve these with me! Practice making number sentences with mental math with this fun game: This lesson is part of the Math Mammoth Grade 3 Curriculum:

These little puzzles are actually equations with an unknown. Here we use a shape for the missing number. Put your thinking caps on and solve these with me! Practice making number sentences with mental math with this fun game: This lesson is part of the Math Mammoth Grade 3 Curriculum:

To subtract a single-digit number from a three-digit number, we can subtract in parts, or use easier, similar problems. I give several examples of these. Practice your mental math with this fun game: This lesson is part of the Math Mammoth Grade 3 Curriculum:

To subtract a single-digit number from a three-digit number, we can subtract in parts, or use easier, similar problems. I give several examples of these. Practice your mental math with this fun game: This lesson is part of the Math Mammoth Grade 3 Curriculum:

I show you how to use an easier, helping problem to add a three-digit and a single-digit number, such as 435 + 6. We simply add 35 + 6 first, to get 41. The answer to the original addition problem is then 441. Then we look at two problems, such as 194 + 8, wherethe answer will go over to the next hundred. Practice mental math with the fun game Fruity Math: This lesson is part of the Math Mammoth Grade 3 Curriculum:

I show you how to use an easier, helping problem to add a three-digit and a single-digit number, such as 435 + 6. We simply add 35 + 6 first, to get 41. The answer to the original addition problem is then 441. Then we look at two problems, such as 194 + 8, wherethe answer will go over to the next hundred. Practice mental math with the fun game Fruity Math: This lesson is part of the Math Mammoth Grade 3 Curriculum:

We look at several subtraction problems (2-digit and 3-digit) where the most effective strategy is to think of the difference between the numbers. This strategy works best when the numbers to be subtracted are close to each other. The last example we look at is the two-digit subtraction 72 - 37. I solve it by finding the difference between 37 and 72 -- essentially "adding up" from 37 to 72, in three different parts. I show arrows with jumps -- like using a number line without tick marks. Practice two-digit mental math with these free online exercises: Play Hidden Picture Game and practice mental subtraction: This lesson is part of the Math Mammoth Grade 3 Curriculum:

We look at several subtraction problems (2-digit and 3-digit) where the most effective strategy is to think of the difference between the numbers. This strategy works best when the numbers to be subtracted are close to each other. The last example we look at is the two-digit subtraction 72 - 37. I solve it by finding the difference between 37 and 72 -- essentially "adding up" from 37 to 72, in three different parts. I show arrows with jumps -- like using a number line without tick marks. Practice two-digit mental math with these free online exercises: Play Hidden Picture Game and practice mental subtraction: This lesson is part of the Math Mammoth Grade 3 Curriculum:

In this mental math lesson, we look at adding and subtracting multiples of ten (20, 30, 40, 50, etc.) to/from a 3-digit number mentally. It is based on place value, and is very easy! First, we do a few of these addition and subtraction problems with the help of a visual model - to show clearly that it is based on place value: we simply add the tens to the existing tens. Then we solve some more challenging problems, a word problem involving Mathy, my mammoth mascot, and lastly, we look at a number pattern of sorts. Practice mental subtraction with this fun hidden picture game: Practice both 2-digit and 3-digit mental math with Mathy's Berry Picking Adventure game: The video is suitable for 2nd and 3rd grade math, and belongs to Math Mammoth Grade 2 curriculum:

In this mental math lesson, we look at adding and subtracting multiples of ten (20, 30, 40, 50, etc.) to/from a 3-digit number mentally. It is based on place value, and is very easy! First, we do a few of these addition and subtraction problems with the help of a visual model - to show clearly that it is based on place value: we simply add the tens to the existing tens. Then we solve some more challenging problems, a word problem involving Mathy, my mammoth mascot, and lastly, we look at a number pattern of sorts. Practice mental subtraction with this fun hidden picture game: Practice both 2-digit and 3-digit mental math with Mathy's Berry Picking Adventure game: The video is suitable for 2nd and 3rd grade math, and belongs to Math Mammoth Grade 2 curriculum: