#21 - Twenty One - #21
by Ashlynn Keck
21
*I chose 21 because April 21st is my golden birthday!
*Ellis Lankster on the New York Jets is number 21. (Go Jets!)
* The factors of 21 are 1,3,7,21.
*21 is composite because it has more than 2 factors.
*21 is odd because it does not have 2 as a factor and it ends in 1.
* April 21st is also Queen Elizabeth's birthday!
*Selena Gomez is age 21.
* Other famous athletes having #21 were Robert Clemente, a Pittsburg Pirate Hall of Fame baseball player who played outfield. Also Mike Eruzione was on the 1980 Winter Olympic Hockey team members who scored the winning goal for the USA team to defeat the Russians. The USA team later won the gold medal.
* The store Forever 21 has very cute clothes to buy.
21 is such a cool number because...
* 21 is considered a lucky number.
* 21 is the number you try to get in black jack.
* 21 is the legal drinking age in Iowa.
* Many people consider you an adult at age 21.
* 21 is the number of shots fired to do a military salute: 21 gun salute.
Factor Tree, Square Numbers and Cubed
The factor pairs of 21 are:
1 × 21
3 × 7
This makes it a composite number because it has more than 2 factors.
* 21 cubed is 9,261
* 21 squared is 441
* The factors of 21 are prime Numbers ( 3 & 7)
Fun Facts, Facts, Facts!
*If you double 21 you get 42.
*Half of 21 you get 10.5.
*21 x 21 = 441.
*The number 21 is the number between 20 and 22.
*The first five multiples of 21 is ... 21,42,63,84,105.
* 21 is a deficient number... 1+3+7+21=32. If you double 21 you get 42, and because 32 is less than 42, it's considered deficient by 10.
LCM and GCF OF 21 and 24
* The Greatest Common Factor of 21 and 24 is 3.