Multiplicación- Multiplication
We all learn elementary math at school. It is said that we count and calculate in our mother tongue or the language we were taught math in.
This may sound weird but I'm sure that not even in other Spanish speaking countries they were taught the way I was. Imagine how this would be expressed in English!!!
15
x 8
-----------
120
This is how I was taught
Cinco por ocho cuarenta.
Cero (meaning escribo o pongo cero) y me llevo cuatro.
Ocho por uno ocho más cuatro que me llevaba doce.
Total 12 (doce) 0 (cero)
Total 120
Do you do it in the same way? I'd never be able to know how to say all these calculations in English.
6 Answers
Eight times five equals forty. Put down the zero in the ones' place and carry the four. Eight times one equals eight plus the four that was carried equals twelve. Put down the two in the tens' place and the one in the hundreds' place. Answer: 120.
Polenta:
It's been over 50 years since I said the words, but I remember the following, very close to your words.
Eight times five is forty. Write down zero and carry the four. Eight times one is eight, add the four to get twelve. Total is one hundred twenty.
Another way, combining a little mental math.
Four times thirty is one hundred twenty.
Nowadays, if I was teaching someone:
Take out your calculator, we're going to do (or multiply) five times fifteen. Hit the five, then hit the X, now enter fifteen and press equal and you get one hundred twenty.
This reminds my of Jethro from the Beverly Hillbillies. He used to practice his gazintas.
Two gazinta ten five times. Six gazinta twelve twice. 
In the UK we call it maths. I was taught your way
15
x8
5 x 8 equals 40. Put the nought under the 5 and carry the 4 under the tens. 8 x 1 equals 8, add to the 4 equals 12. Put the 2 in the tens column and the 1 in the hundreds.
They introduced new maths later and it may be younger people have been taught differently. In fact we had a teacher who said we should be able to say our tables up to 20 so that would have been easy. Nowadays maths teachers would probably say zero not nought.
When I was a young child a £ had 240 pennies and there were twelve pennies in a shilling. So 120 would have been ten shillings! Decimal coinage made it much easier.
Now as a mental arithmetic exercise I would say 10 x 15 equals 150 take away (subtract) 2 X 15 which is 30.
However, though I passed my school exam in Maths and worked out double entry bookkeeping and taxes on an estate, I am not as numerate as some here.
"8 * 15"
En la mente multiplico 8 * 5=40. Lo recuerdo. Entonces 8*10=80. Lo recuerdo. Entonces 40+80=120
Otro truco en el caso de dos números que terminan en "5" si son iguales (1515, 2525, 35*35, etc.).
Multiplique la columna de los 10. por ese dígito + 1 y pega "25" al fin.
1515 = 1 * 2 + "25"=225 2525 = 2 * 3 + "25"=625 3535 = 3 * 4 + "25"=1.225 4545 = 4 * 5 + "25"=2.025 .... 9595 = 9 * 10 + "25"=9.9025 ..... 205205=20 *21 + "25"=42.025
I remember it as the "rule of 9's". I can't remember exactly how it works. 50+ years ago, my Gosh! What little that I do remember is that any number, regardless of length is always divisible by 9 if the individual digits add up to 9.
1.234=10=1 No 16.589.745.877=67=13=4 No 1,683=18=9 Sí 18=9 Sí 2.017=10=1 No 2.016=9 Sí 91101=12=3 No
Etc.
When I was a kid after learning the multiplication tables ( only up to ten) we were taught multiplications of two, three or more digits. Later we were taught what they called "la prueba del nueve"
I can't draw it here but it's like a very big X and we had to calculate four numbers that were written on top of the X , at the bottom of the X and on both sides of the X. These latter ones should be identical. This meant the calculation was ok. We checked the multiplication through this "prueba del nueve". Of course we couldn't check with calculators because they didn't exist.
Now I ask young people and they don't know what I'm talking about. Has anyone studied this "prueba del nueve"? And how is it called in English?
