Gauss' method for addition relies on the fact that you can 'pair' certain numbers together. Look at the example:
1+2+3+4+5+6+7+8+9+10
We could manually add all these together from left to right but a clever way to think about this is if we add together the ends of the sum (10+1) we get 11. If we then move one in from the ends and add these (2+9) we also get 11. This means that 1+2+...+9+10 is the same as 11+11+...+11+11.
Because each 2 numbers adds to 11 we know the total number of 11's we have to add together is the length of the sum divided by 2. In our case 5 (10 ÷ 2). We need to add 5 lots of 11 to get our answer. This is the same as 11 × 5 which is easily seen to be 55.
(If you add the 10 numbers together on a calculator you'll see 1+2+3+4+5+6+7+8+9+10 = 55) so this method really makes it a lot quicker.
Looking at your sequence, if we pair the ends together we get 401 (400+1) and we multiply this by the length of the sequence divided by 2. In your case, 200 (400 ÷ 2).
So the sum of all the numbers from 1 to 400 must be 401 × 200 = 80,200.
Remember the steps:
1. Pair the ends together and add them
2. Times this number by the length of the sequence halved
Hope this helps.
Answer:
3/13
Step-by-step explanation:
There are 52 card in a deck of cards
12 of them are face cards 3 cards *4 suits =12
P (face card) = 12/52 = 3/13
Answer:
454
Step-by-step explanation:
Answer:
Step-by-step explanation:
Base fee = $17.99
Additional charge = $0.95 for each mile driven
If Kevin paid $157.64 when he returned the truck and we want to find out how many miles he drove the truck, step 1 would be to subtract the base fee.
157.65 - 17.99 = 139.65
This means that the remaining $139.65 is how much he paid for the miles he drove.
Since we know each mile costs $0.95.
Simply divide $139.65 by $0.95 to work out how many miles he drove.
Miles driven = 139.65 / 0.95 = ?
8 16 32 64 128 are the next four terms to the sequence
