## Practice- Eleven times a two-digit number
- Eleven times a three-digit number
- Square of a two-digit number ending in 5
- Twin tens, unit compliments
- One-digit number times a number between 10 and 20
- Both numbers between 10 and 20
- One digit number plus two digit number
- Two digit number plus two digit number
- Three digit number plus three digit number
- Hundred compliments
- Two digit number minus two digit number
- Three digit number minus three digit number
- Thousand compliments
- Two by ones
- Three by ones
- Divisibility by 2, 5, or 10
- Divisibility by 4
- Divisibility by 8
- Divisibility by 3, 6, or 9
- Divisibility by 11
- Divisibility by 7
## Related Links |
## Chiarvalle Montessori Math ClubWelcome to everybody in math club and anyone else who's interested in mental math! ## April 4, 2012Finally finished the divisibility pages. Enjoy! ## March 22, 2012We looked at divisibility rules for 2, 5, 10, 4, 8, 3, 9, 11, 6, 12, and 7. Setting up the practice pages turned out to be harder than I thought. Sorry folks! Give me a few more days! ## March 15, 2012Today we reviewed multiplication. Next week—division. Our last meeting! ## March 8, 2012Today we learned how to multiply a one digit number by a two or three digit number - Two by ones
(Example: 76 × 4 = 304, since 4 × 70 + 4 × 6 = 280 + 24 = 304) - Three by ones
(Example: 726 × 3 = 2178, since 3 × 700 + 3 × 20 + 3 × 6 = 2100 + 60 + 18 = 2178)
## March 1, 2012This week, most of our students were getting ready for the Interest Fair, so we had a review. ## February 23, 2012Today we learned about thousands compliments and how to use compliments for making change. We also reviewed some of our other math tricks. - Thousand compliments
(Example: Complement of 547 is 453, since 5+4=9, 4+5=9, and 7+3=10)
## February 16, 2012Today we learned some more addition and subtraction tricks. After you've practiced the hundred compliments, go back to the addition and subtraction problems. Try to use compliments in addition problems with carrying or subtraction problems with borrowing. - Three digit number plus three digit number
(Example: 477 + 387 = 864, since 477 + 300 = 777 and 777 + 87 = 864) - Two digit number minus two digit number
(Example: 57 - 38 = 19, since 57 - 30 = 27 and 27 - 8 = 19) - Three digit number minus three digit number
(Example: 574 - 382 = 192, since 574-300=274 and 274-82=192) - Hundred compliments
(Example: Complement of 32 is 68, since 3+6=9 and 2+8=10.
Here's an example of addition using a compliment:
477 + 387 = 864, since 477 + 400 = 877 and 877 - 13 = 864 (13 is the compliment of 87, so 387+13=400) Here's an example of subtraction using a compliment: 574 - 382 = 192, since 574 - 400 = 174, and 174 + 18 = 192 (18 is the compliment of 82, so 382+18=400) ## February 9, 2012Today we reviewed some of the tricks we learned last time and added some new ones: - One digit number plus two digit number
(Example: 47 + 6 = 53, since 7 + 6 > 10 and 7 + 3 = 13) - Two digit number plus two digit number
(Example: 47 + 38 = 85, since 47 + 30 = 77 and 77 + 8 = 85)
## January 26, 2012Here are the mental math tricks we practiced today. Click on the links for some extra practice. - Eleven times a two-digit number
(Example: 11 * 62 = 682, since 6+2=8) - Eleven times a three-digit number
(Example: 11 * 341 = 3751, since 3+4=7 and 4+1=5) - Square of a two-digit number ending in 5
(Example: 65 squared is 4225, since 6*7=42 and 5*5=25) - Twin tens, unit compliments
(Example: 83 * 87 = 7221, since 8*9 = 72 and 3*7=21) - One-digit number times a number between 10 and 20
(Example: 6*13 = 78, since 6*10=60 and 6*3=18) - Both numbers between 10 and 20
(Example: 14*17=238, since 14+7=21, 21*10=210, 4*7=28, 210+28 = 238)
Leone Learning Systems, Inc. (LLS) is a North Shore company that provides online courses for kids anywhere and local teaching and tutoring services for students in Chicago and the Northern Suburbs of Chicagoland. LLS also provides a free geometry software package for children age 6 and up, and free resources for teachers and parents. This site includes information about tutoring and classes provided, learning activities for kids, lesson plans, and ongoing software and curriculum research and development efforts. |