For today's Math Trick Monday, let's look at a cool use of both commutativity and associativity. When we multiply by 25, we can easily think of that as multiplying by 0.25 and then 100. Since 0.25 (or 25%) is the same as 1/4, rather than multiply by 25, we can divide the number by 4. If 4 goes into it evenly, we simply write down that result with two zeroes after it. If there's a remainder, then we simply write that remainder times 25 itself. So, 25 for remainder 1, 50 for remainder 2, and 75 for remainder 3. Subscribe: http://bit.ly/SubTimRicchuiti | Enable ALL push notifications 🔔 This is a great trick if you participate in UIL Number Sense or are looking for other fast mental math techniques. Follow for more number sense tips. Follow Tim Ricchuiti: TikTok: https://www.tiktok.com/@polymathematic Twitter: https://twitter.com/poly_mathematic Instagram: https://www.instagram.com/polymathematicnet Reddit: https://www.reddit.com/user/polymath-matic Watch more Math Videos: Math Minutes: https://www.youtube.com/playlist?list=PLrc8spN1b3jmVFYwHiuMzCYJ0y_yiwUge Number Sense: https://www.youtube.com/playlist?list=PLrc8spN1b3jksKkY_oarNFEFAHjrIV97U Math Minis: https://www.youtube.com/playlist?list=PLrc8spN1b3jkQynJ5heNvSs72gCPj_hwj MATHCOUNTS: https://www.youtube.com/playlist?list=PLrc8spN1b3jlqDkZXtby9lnEaOBy7-ZY0