Blog Post #65: For Dear Colleagues Kate and James

Dear Readers,

This post is specially dedicated to two dear colleagues: Kate, whose birthday is coming on 29 February in less than two days’ time, and James, whose 50th birthday is coming in less than two weeks’ time on 11.3.2020.

James is pictured on the right of the following photo at a school Christmas dinner some years ago.

Fast Warm-Up!

As a quick warm-up puzzle in honour of Kate (who is younger than James), can you figure out Kate’s exact date of birth if I tell you that Kate was born k years ago, where k is a two-digit palindromic whole number?

Using 11, 3, 20 and my favourite bonus 3 again for James, Kate & Everyone!

Challenge 1: Use the numbers 3, 3, 11 and 20 to make the target number 50. You can also use +, -, x, / or (    )  as you wish.

Challenge 2: Use the numbers 3, 3, 11 and 20 to make the target number 44. You can also use +, -, x, / or (    )  as you wish.

Challenge 3: Use the numbers 3, 3, 3, 3, 11, 11, 20 and 20 to make the target number 2020, to wish everyone extra happiness this year! You can also use +, -, x, / or (    )  as you wish.

Bonus Chess Challenge

This position was reached after White’s 21st move in a recent grandmaster clash. Black continued 21…Bxg2+, counting on 22 Kxg2 Rxd3 23 Bxc7 Rd2+ 24 Kh1 Rxc7 25 Re8+ Bf8, as actually happened in the game. However, he had presumably missed that 26 Ne4! was coming. Why did Black then resign?


Fast Warm-Up: Given that leap years (with 29 February, Kate’s birthday) generally occur every 4 years, the two-digit palindromic number k must be a multiple of 4. We were also basically given that k is less than 50. Therefore, k=44, and Kate’s exact date of birth was 29.2.1976, forty-four years ago.

Challenge 1: 3 x 11 + 20 – 3 = 50.

Challenge 2: (11-3) x 3 + 20 = 44.

Challenge 3: 3 x 3 x 11 x 20 + 3 x 3 + 11 + 20 = 2020.

Bonus Chess Challenge: After 26 Ne4!, Black was dead lost on account of 26…Rdxc2 27 Nf6+! gxf6 28 Rg1+.

Congratulations if you found those, or any other good solutions of your own.

Please join me again soon for further fun puzzles!


Author: Paul A. Motwani

My name is Paul Motwani, but my colleagues, my students and their parents mostly call me "Mr. Mo"! My middle initial, A, stands for Anthony, because I was born on the official feast day of St. Anthony of Padua, the patron saint of miracles and of lost souls. I love teaching Mathematics and Chess, and giving fun-packed talks and shows in schools and clubs. The popular ingredients of Math, Chess, Mystery and Magic are my "Fantastic Four", and I give prizes too! I am an International Chess Grandmaster, and (loooooong ago!) I was the World Under-17 Champion. I am the author of five published chess books and hundreds of newspaper articles. I live with my wonderful wife and son in Belgium. I also love music, movies and puzzles. I blog at My e-mail address is You can find me on Facebook, too.

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