Mathematical ability is among the most important determinants of prospering in the labour market. Using multiple representative datasets with learning outcomes of over 2 million children from rural India in the age group 8 to 16 years, the paper examines the prevalence of gender gap in performance in mathematics and its temporal variation from 2010 to 2018. Our findings from the regressions show significant gender gap in mathematics, which is not observable for reading skills. This difference in mathematics scores remains prevalent across households of different socio-economic and demographic groups. This gap is found to be persistent over time and it appears to increase as the children get older. We also find significant inter-state variation with the north Indian states lagging behind considerably and the south Indian states showing a reverse gender gap. As an explanation to this, we observe evidence of a robust association between pre-existing gender norms at the household and district level with higher gender gap. The findings, in light of other available evidence on the consequences of such gaps, call for the need to understand these gender specific differences more granularly and periodically to inform gender-specific interventions.