http://mathbitsnotebook.com/JuniorMath/RatioProportion/RPProportions.html
Arithmetic Series and Sums https://mathbitsnotebook.com/Algebra2/Sequences/SSGauss.html
https://www.mathsisfun.com/algebra/sequences-sums-arithmetic.html
Exercises:
- Six years ago, I was 6 years old. Six year form now on, I will be ? years old?
- 2021 – 2020 + 2019 – 2018 + …… + 3 – 2 +1 – 0 = ?
- 100 – 98 + 96 -94 + …… + 4 – 2 = ?
- I read 1 page on March 1st, 2 pages on March 2nd. Each day in March, I read as many pages as the day number. All together, how much did I read in March.
- 1 + 2 + 4 + 8 + 16 + 32 + 64 + 128 = ? (2^8 – 1) Geometric Sequences and Sums, Covid Spreading
http://www.mathematicshed.com/uploads/1/2/5/7/12572836/decimalwordprobsgood.pdf
http://aj050.k12.sd.us/Math/Story%20Problem%20Practice.pdf
https://code4kids.ca/wp-content/uploads/2021/04/Steps.pdf
2020Gauss7Contest1 + 3 + 9 + 27 + 81 … +3^n = ?
https://www.mathsisfun.com/algebra/sequences-sums-geometric.html#:~:text=1%2C%202%2C%204%2C%208,the%20previous%20term%20by%202.
https://math.stackexchange.com/questions/1930368/proof-for-formula-for-sum-of-sequence-3-9-27-81-3n