How many kJ is 10 kcal?
10 kcal = 41.84 kJ
It is 41.84 kJ, so saying 42 kJ is fine — rounding is within 0.5%.
And how many kcal is 10 kJ?
10 kJ = 2.39 kcal
Formula: kJ = kcal × 4.184
kcal to kJ around this value
1 kcal4.18kJ
2 kcal8.37kJ
3 kcal12.55kJ
4 kcal16.74kJ
5 kcal20.92kJ
6 kcal25.1kJ
7 kcal29.29kJ
8 kcal33.47kJ
9 kcal37.66kJ
10 kcal41.84kJ
11 kcal46.02kJ
12 kcal50.21kJ
13 kcal54.39kJ
14 kcal58.58kJ
15 kcal62.76kJ
16 kcal66.94kJ
17 kcal71.13kJ
18 kcal75.31kJ
19 kcal79.5kJ
20 kcal83.68kJ