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MathBait™ Multiplication

Fast Adding

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Ready to build some confidence while practicing multiplication and finding challenging products with ease? Fast Adding is the game for you. Using Napier's Bones, students race to find what may seem like a difficult product (such as 87×5). Students will be proud and amazed when they discover they can quickly and easily find the product using only simple addition!


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Playing with Napier's Bones







This activity is great for students developing fluency and ready for 2-digit multiplication. Fast adding is a great confidence builder. Consider using this activity as an introduction to multiplying large values with Napier's Bones.

Fast Adding is a simple activity that helps students practice their addition skills and fluency while building confidence in multiplication. To set up this activity, teachers should pick ~10 multiplication problems that do not involve carrying. As students advance, any value may be selected to also encourage students to consider place value.

We recommend starting with 12's. Some multiplication tables include 12's and it can be helpful for students to recognize multiples of 12 for tasks such as conversion between feet and inches.

Begin by asking students what the numbers on a bone represents (multiples). Next, ask them what happens when we put more than one bone together? When using multiple bones we create a multi-digit number. For instance, grabbing the 1 and 2 bone allows us to make the number 12.

Ask students to "read" the 12 bone. If needed, display how the bones work. We must sum the joints created, thus the first row of the 12 bone reads 0/10/2 we read this as 0 1+0 2 or 012 which is of course the number 12.

Allow students time to practice reading the bones. Create different combinations. When ready, begin Fast Adding.

Explain to students you will provide a multiplication fact. Students will use the bones to create the first value and then shout out the product. For example, we could ask students to find 87×5. Students must collect the 8 and 7 bone, navigate to the 5th row to find 4/03/5, and do the very simple sum to determine 87×5=435.

Continue to play a few rounds. While this seems like a very basic game you will be thrilled with the engagement. Because it is easy, students don't feel the anxiety and pressure that often comes with a new and complex topic. Students will go home and share with their families how they can multiply big numbers with ease. They will feel confident so that when we try to find multi-digit products without the bones, they are prepared for the challenge.

stacking 40 and 35 to compute 87 times 5 mentally

Ask students if they might be able to determine 87×5 mentally without the bones. This should ideally take place after students have experience and understand how the bones work. They may come up with some great ideas. For instance, to quickly transition to multiplying 2-digit by 1-digit numbers without the bones, find each product and stack the result. If asking a student what is 92×4, their experience with the bones can help them to quickly calculate 2×4=8 and 9×4=36 to put together 368. Extended play with the bones will greatly increase student multiplication skills.

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