<Tr> <Td> Mg </Td> <Td> 12 </Td> <Td> 23 </Td> <Td> 35.01734 (43) #</Td> <Td> 70 (40) ms </Td> <Td> β, n (52%) </Td> <Td> Al </Td> <Td> (7 / 2 −) #</Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> β (48%) </Td> <Td> Al </Td> </Tr> <Tr> <Td> Mg </Td> <Td> 12 </Td> <Td> 24 </Td> <Td> 36.02300 (54) #</Td> <Td> 3.9 (13) ms </Td> <Td> β </Td> <Td> Al </Td> <Td> 0 + </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> Mg </Td> <Td> 12 </Td> <Td> 25 </Td> <Td> 37.03140 (97) #</Td> <Td> 40 #ms (> 260 ns) </Td> <Td> β </Td> <Td> Al </Td> <Td> 7 / 2 − #</Td> <Td> </Td> <Td> </Td> </Tr>

Which is the number of neutrons present in the magnesium-25 isotope