This action research is anchored on exploring a teaching method that innovatively blends 'mental math enhancement techniques' with David Marsh's CLIL (Content and Language Integration in Learning) pedagogy. Both these stand as fundamental factors and profoundly influence the quality of mathematics learning. The decline in mathematical reasoning abilities of students has become a growing concern over the years. This research makes an effort towards addressing this by strengthening the basic mathematical concepts with the help of above method. The study aimed at investigating the effectiveness of the program by determining if there is (a) a difference in pre- and post-test scores. (b) significant increase in student attitude towards mathematics, (any change in self-concept and attitude before and after the program) 116 students of Grade 6, 7, and 8, divided into groups through stratified sampling participated in the weekly arithmetic sessions, daily quiz activities, math communications/number talks, and language integrated CLIL sessions. This 'curriculum-integrated research' employed experimental method using pre-test & post-test experimental group design. The results revealed that the CLIL integrated/mental math enhancement technique significantly improved the mathematical reasoning abilities in a particular class. The attitudes towards the subject also proved to rely positively on mathematical performance and vice versa.