Answer: The number 4 indicates 4 electrons.
Explanation: We are given an electronic configuration, which is:

Here,
- The letters denote the sub-shells of an element.
- The numbers written before the letters which are 1, 2 and 2 represents the Principle Quantum Number and these represents the energy level of the sub-shells.
- The number which are written in the superscripts which are 2, 2 and 4 denotes the electrons which are present in the sub-shell.
Hence, 4 indicates 4 electrons present in 2p sub-shell.
Basically this is used in calculating the nuclear binding energy by converting the mass defect (calculated first) to energy and if we recall, Einstein's equation E=mc2 is the perfection equation to use because E=mc2 in which E represents units of energy, m represents units of mass, and c 2 is the speed of light squared.
if 105 grams burns completely
therefore
105 ×22.4/48=49