Ahsan, F.F. 2025. The Effect of Numbered Heads Together (NHT) on Elementary School Students’ Mathematical Problem-Solving Ability in Geometry. Mathline : Jurnal Matematika dan Pendidikan Matematika. 10, 3 (Aug. 2025), 659–670. DOI:https://doi.org/10.31943/mathline.v10i3.787.