[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).