Maths Quiz (Round 1)

[Desgracias]

So, kids can be a bit of a struggle to deal with. I mean, they're immature, whiny, and rather annoying. I'm a kid too, but not just any kid; I'm actually a master of multiplication. I can calculate rather difficult questions off the top of my head, such as 19x16. (The answer is 304 for your information). I know my times tables up to 20 (400), squares up to 30 (900), triangular numbers up to 20 (210), cubes up to 10 (1000), and hypercubes up to 10 (10 000, hypercubes are what I call numbers that are a 4th power or a square squared). I know this is rather unrelated to what this forum is for...

but hey this is the everything else section we can talk about whatever we want here

Anyways, I'm also good with number bases and conversion, too. This is why I have prepared a maths quiz for you guys to see how good you are when it comes to my interests. This is only round 1, which is about multiplication. Round 2 will be about numerical sequences (such as squares and cubes), and round 3 will be about number bases and conversion. Anyways, you have 10 math questions to answer. I have given you all the time needed, and remember this: you don't have to do all of them at once.

Try not to do them with a calculator.

Without further ado, here are the questions!

1. 19x16=
2. 16x17=
3. 15x14=
4. 17x13=
5. 11x19=
6. 16x18=
7. 19x18=
8. 19x7=
9. 15x19=
10. 17x19=

Good luck! 

From Uli, 11 years old. Thank you for reading.

[Dav999]

Alright, I'll give it a try. I don't know any of these by heart but I'll calculate them in my head and then write down my thinking steps.

1. 19x16 = 20x16-16 = 320-16 = 304
2. 16x17 = 42+60+70+100 = 42+230 = 272
3. 15x14 = 30x7 = 210
4. 17x13 = 20x13-39 = 260-39 = 221
5. 11x19 = 190+19 = 209
6. 16x18 = 16x16+2x18 = 256+36 = 262+30 = 302 288 derp. 2x18 should've been 2x16 and 26+3≠30. At least my programmer brain knew 16x16
7. 19x18 = 20x18-18 = 360-18 = 342
8. 19x7 = 20x7-7 = 140-7 = 133
9. 15x19 = 15x20-15 = 300-15 = 285
10. 17x19 = 285+2x19 = 285+38 = 293+30 = 323

[Desgracias]

I see you got them all right! Congrats Dav! There is also a trick with the 19 times table: Add 20, then take 1 away.

From Uli, 11 years old. Thanks for reading.