[Italian.  Dot product:  prodotto scalare o prodotto interno.  Cross product: prodotto vettoriale]

•  u = i − 2j + 3k, v = 3i + j − 4k.   u+v = ?,  u·v = ?,  u×v = ?,  ||u|| = ?,  ||v|| = ?,  ∠uv = ?

Enter a1, a2, ...
1, -2, 3
Enter b1, b2, ...
3, 1, -4
sum
4, -1, -1
dot
-11
cross
5, 13, 7
||u|| = 3.7416573867739413, ||v|| = 5.0990195135927845
using this I get:
cos(∠uv) = dot / (||u||·||v||) = -0.5765566601970551
∠uv = acos(") = 2.1853044005495423 = 125.20871910285513°  (125.2°).

•  AFB3 base 16 → ? base 10
A → 10, F → 15, B → 11, 3
Enter a1, a2, ...
3, 11, 15, 10
Enter b1, b2, ...
1, 16, 256, 4096
dot
44979

•  The caloric value of proteins, fats and carbohydrates is 4.1, 9.3 and 4.1 kcal/g respectively.  The percentage (i.e. the number of grams per 100 grams of substance) of proteins, fats and carbohydrates that bread has: 8, 1, 55.  How many Kilocalories are provided by 1 hg of bread?

Enter a1, a2, ...
4.1, 9.3, 4.1
Enter b1, b2, ...
8, 1, 55
dot
267.59999999999997
I that I round to 268 (or to 270).

•  Some rectangles.
first side:     12, 21, 17, 19, 28, 25, 13, 21, 16
second side: 32, 26, 18, 29, 15, 14, 24, 31, 23
I use [sum]: 44, 47, 35, 48, 43, 39, 37, 52, 39   (semiperimeters)
I use [prod]: 384, 546, 306, 551, 420, 350, 312, 651, 368   (areas)

•  The maximum and minimum temperatures of some days and the temperature jumps.
first side:      21, 18, 17, 23, 20, 22
second side: 16, 11, 11, 19, 15, 16
I use [diff]:     5, 7, 6, 4, 5, 6

Calculations are done with many digits and not with base ten; you can round the results using this pocket calculator.

•  The maximum and minimum temperatures of some days and the temperature jumps.
first side:      21.3, 18.5, 17.6, 23.1, 20.7, 22.4
second side: 16.1, 11.5, 11.4, 19.2, 15.3, 16.7
I use [diff]:     5.199999999999999,7,6.200000000000001,3.900000000000002,5.399999999999999,5.699999999999999

With the pocket calculator:
[Round] 1
Enter data
5.199999999999999,7,6.200000000000001,3.900000000000002,5.399999999999999,5.699999999999999
[round]
5.2, 7, 6.2, 3.9, 5.4, 5.7