Using an Improvised Abacus to Assist Samproso M/A Junior High School Level One Pupils to Overcome the Problem of Place Value Concept in Mathematics. int.jour.sci.res.mana [Internet]. 2019 Jun. 4 [cited 2024 May 5];7(06):144-65. Available from: https://ijsrm.net/index.php/ijsrm/article/view/2175